Formation method of metal layer on resin layer

ABSTRACT

A printed wiring board having a conductor circuit comprising a copper layer adjacent to an insulating layer and an electroless gold plating, wherein the insulating layer has ten-point mean surface roughness (Rz) of 2.0 μm or less is provided. According to the present invention, there is no such a defect that gold plating is deposited on a resin, and fine wiring formation with accuracy is realized.

This application is a Divisional application of application Ser. No.10/986,913, filed Nov. 15, 2004 now U.S. Pat. No. 7,615,277, thecontents of which are incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a printed wiring board and its productionmethod. Further, the invention relates to a formation method of a resinlayer on a metal layer, an inner conductor circuit treatment method, anda multilayer circuit board.

2. Description of the Related Art

Recently, electronic devices have been required to be compact,lightweight and high speed, and high densification of printed wiringboards has been advanced. Along with that, production of a printedwiring board by a semi-additive method using electroplating has beendrawing an attention. As a semi-additive method, Japanese PatentApplication Laid-Open No. 10-4254 discloses a method involving formingholds to be IVH in the resin surface in which a circuit is to be formedby laser; surface-roughening the resin surface with several μm bychemical roughening or plasma treatment; supplying a Pd catalyst;carrying out electroless plating in about 1 μm-thickness, forming aresist layer for pattern electroplating, carrying out wiring formationby pattern electroplating, and then removing the resist and a powersupply layer existing in the portion other than the circuit and in sucha manner the method makes more finer wiring formation possible ascompared with a subtractive method with a high side etching degree.Japanese Patent Application Laid-Open No. 2003-158364 discloses a methodof forming a circuit using a separable metal foil with a thickness of 5μm or thinner formed on a supporting metal foil. The method makesproduction of a printed wiring board with a high reliability possiblewithout requiring electroless plating of the surface of an insulatingresin layer. However, according to these methods, the roughened shapeinversely interferes the fine wiring formation. Moreover, the electriccharacteristics are deteriorated by the roughened shape. Japanese PatentApplication Laid-Open (JP-A) No. 7-221444 discloses a method involvingforming a copper layer with about 1 μm thickness on one face of apolyimide film by using an electron beam evaporation apparatus andlayering the layer on an intermediate circuit by an adhesive or aprepreg to form an electric power supply layer. However, the substrateis very expensive and thus does not become popular.

After formation of the circuit in such a manner, gold plating on theoutermost layer of the substrate is sometimes carried out. JP-A No.7-221444 discloses a method of electrolytic gold plating to improve theconnection reliability of terminals of a substrate and a semiconductorchip. As the gold plating method, there are an electroless gold platingmethod and an electrolytic gold plating method. Between them, theelectroless gold plating method which requires no electric power supplyis advantageous in high densification. However, in the case of goldplating after the circuit formation, a trouble that the gold plating isdeposited on the resin sometimes occurs at the time of electroless goldplating according to the above-mentioned method disclosed in JP-A No.10-4254. Especially, in the case the wiring pitches become 80 μm ornarrower, the trouble occurs more frequently. Also, in the case of goldplating after the circuit formation, a trouble that the gold plating isdeposited on the resin sometimes occurs owing to remaining of a copperfoil on the resin at the time of electroless gold plating according tothe above-mentioned method disclosed in JP-A No. 2003-158364.

Further, in recent years, to satisfy high densification of a substrateand speed up of signal transmission, built up type multilayer wiringboards have been used. JP-A No. 10-242638 discloses a method involvingsurface roughening a conductor circuit of a core substrate with acopper-nickel-phosphorus alloy, forming an insulating layer thereafter,and forming a conductor circuit on the insulating layer. JP-A No.2000-282265 discloses a method of roughening in micron order the coppersurface by using an aqueous solution containing an inorganic acid and acopper-oxidizing agent as main agents and at least one kind azole andetching suppressing agent as auxiliary agents. JP-A No. 9-246720discloses a method involving forming continuous projected and recessedparts with height in a range of 1.5 to 5.0 μm by micro-etching andcarrying out chromation and treatment with a coupling agent. Asdescribed, there are many methods for treating conductive circuits, andthe methods can be divided broadly into methods of covering copper withan anti-rust treatment metal other than copper, methods of forming theroughened surface in micron order by roughening the conductor surface byetching or plating, and combination of these methods.

Along with the high densification of the substrate, the wiring has beenmade finer. Presently, it is highly required to form wiring withL/S=20/20 μm or lower by fine wiring formation techniques represented bythe semi-additive method.

However, these methods tend to cause problems that the electricproperties are deteriorated: that plating is deposited on the portionother than the conductor circuits along with the advanced fineness ofthe circuits: and that plating between fine circuits is insufficient.Further, there occur problems that the resistance of the conductor isincreased because of etching of the conductor circuit and the dispersionof the wiring becomes wide.

SUMMARY OF THE INVENTION

The embodiments of the invention are the following (1A) to (17A).

-   (1A) A printed wiring board having a conductor circuit comprising a    copper layer adjacent to an insulating layer and an electroless gold    plating, wherein the insulating layer has ten-point mean surface    roughness (Rz) of 2.0 μm or less.-   (2A) The printed wiring board according to (1A), wherein the copper    layer has a double-layer structure comprising a copper foil and    electrolytic copper plating.-   (3A) The printed wiring board according to (1A), wherein the copper    layer has a triple-layer structure comprising a copper foil, an    electroless copper plating, and an electrolytic copper plating.-   (4A) A printed wiring board having a conductor circuit comprising a    copper layer adjacent to an insulating layer and an electroless gold    plating, wherein the face of the copper foil contacting the    insulating layer is not practically surface-roughened.-   (5A) The printed wiring board according to (4A), wherein the copper    layer has a double-layer structure comprising a copper foil and    electrolytic copper plating.-   (6A) The printed wiring board according to (4A), wherein the copper    layer has a triple-layer structure comprising a copper foil, an    electroless copper plating, and an electrolytic copper plating.-   (7A) The printed wiring board according to one of (2A), (3A),-   (5A), and (6A), wherein the electrolytic copper plating is formed by    patterned electrolytic copper plating.-   (8A) The printed wiring board according to one of (1A) to (7A),    wherein an electroless nickel plating exists immediately under the    electroless gold plating.-   (9A) The printed wiring board according to one of (1A) to (8A),    wherein the minimum pitch of the conductor circuit is 80 μm or    narrower.-   (10A) A production method of a printed wiring board involving    forming a circuit on a substrate which has a copper foil on an    insulating layer and carrying out electroless gold plating on the    circuit, wherein the face of the copper foil contacting the    insulating layer has ten-point mean surface roughness (Rz) of 2.0 μm    or less.-   (11A) A production method of a printed wiring board involving    forming a circuit on a substrate which has a copper foil on an    insulating layer and carrying out electroless gold plating on the    circuit, wherein the face of the copper foil contacting the    insulating layer is not practically surface-roughened.-   (12A) The production method of a printed wiring board according to    (10A) or (11A) including steps of forming holes penetrating the    insulating layer and the copper foil for interlayer connection,    carrying out electroless copper plating in the holes and on the    copper foil, forming a resist layer on the portion where no    conductor circuit is to be formed, carrying out patterned    electrolytic copper plating in the holes and on the copper foil,    removing the resist layer, and removing the copper foil and the    electroless copper plating in the portions other than the portion to    be the conductor circuit by etching.-   (13A) The production method of a printed wiring board according to    (12A), wherein the step of removing the portions other than the    portion to be the conductor circuit by etching is carried out by    etching with a chemical solution containing sulfuric acid and    hydrogen peroxide as main components.-   (14A) The production method of a printed wiring board according to    (13A), wherein the concentration of sulfuric acid is 5 to 300 g/L    and the concentration of hydrogen peroxide is 5 to 200 g/L.-   (15A) The production method of a printed wiring board according to    one of (10A) to (14A) involving electroless nickel plating before    electroless gold plating.-   (16A) The production method of a printed wiring board according to    one of (10A) to (15A) involving electroless palladium plating before    electroless gold plating.-   (17A) The production method of a printed wiring board according to    one of (10A) to (16A), wherein the minimum pitch of the conductor    circuit is 80 μm or narrower.

According to the above embodiments of the invention, there is no such adefect that gold plating is deposited on a resin, and fine wiringformation with accuracy is realized.

Further, the embodiments of the invention are the following (1B) to(20B).

-   (1B) A printed wiring board comprising an insulating layer and a    conductor circuit, wherein a part of the conductor circuit is made    of an electrolytic copper foil and the surface in the inner layer    side of the conductor circuit has ten-point mean surface roughness    (Rz) of 2.0 μm or less and an adhesive layer is inserted between the    conductor circuit and the insulating layer.-   (2B) The printed wiring board according to (1B), wherein the    thickness of the adhesive layer is 0.1 to 5 μm.-   (3B) The printed wiring board according to (1B) or (2B), wherein the    thickness of the adhesive layer is ⅛ or thinner than the thickness    of the insulating layer.-   (4B) The printed wiring board according to one of (1B) to (3B),    wherein the adhesive layer contains an organic material and an the    insulating layer comprises a composite material of an inorganic    material and an organic material.-   (5B) The printed wiring board according to one (1B) to (4B), wherein    the conductor circuit is entirely covered with the adhesive layer.-   (6B) The printed wiring board according to one of (1B) to (5B),    wherein the entire body of the conductor circuit is not    substantially surface-roughened.-   (7B) The printed wiring board according to one of (1B) to (6B),    wherein a resin having 20 ppm/° C. or lower thermal expansion    coefficient in the transverse direction (CTE X, CTE Y) in a range of    0 to 150° C. is used for the insulating layer.-   (8B) The printed wiring board according to one of (1B) to (7B),    wherein a resin having a tensile strength of 200 MPa or higher at    20° C. is used for the insulating layer.-   (9B) The printed wiring board according to one of (1B) to (8B),    wherein a resin having a dielectric dissipation factor of 0.01 or    lower at 1 GHz is used for the insulating layer.-   (10B) The printed wiring board according to one of (1B) to (9B),    wherein a resin having a dielectric constant of 0.3 or lower at 1    GHz is used for the insulating layer.-   (11B) The printed wiring board according to one of (1B) to (10B),    wherein a thermosetting resin composition containing (A)    polyphenylene ether or a modified polyphenylene ether is used for    the insulating layer.-   (12B) The printed wiring board according to one of (1B) to (11B),    wherein (B) a thermosetting resin composition containing a cyanate    ester compound is used for the insulating layer.-   (13B) The printed wiring board according to one of (1B) to (12B),    wherein (C) a thermosetting resin composition containing an epoxy    compound is used for the insulating layer.-   (14B) The printed wiring board according to one of (1B) to (13B),    wherein (D) a thermosetting resin composition containing a polyamide    imide compound is used for the insulating layer.-   (15B) The printed wiring board according to one of (1B) to (14B),    wherein the peel strength of the insulating layer and the conductor    circuit with 1 mm width is 0.6 kN/m or higher.-   (16B) The printed wiring board according to one of (1B) to (15B),    wherein the peel strength of the insulating layer and the conductor    circuit with 1 mm width is 0.4 kN/m or higher after heating at    150° C. for 240 hours.-   (17B) A production method of a printed wiring board involving    forming a conductor circuit by patterned electroplating using a    metal foil firmly fixed on an insulating layer as an electric power    supply layer, wherein the metal foil is not surface-roughened in    both faces and an adhesive layer is inserted between the insulating    resin and the metal foil.-   (18B) The production method of a printed wiring board according to    (17B), wherein the metal foil has ten-point mean surface roughness    (Rz) of 2.0 μm or less in both faces.-   (19B) The production method of a printed wiring board according to    (17B) or (18B), wherein the metal foil has a thickness of 3 μm or    thinner.-   (20B) The production method of a printed wiring board according to    one of (17B) to (19B), wherein an electroless plating layer is    formed on the metal foil.

According to the above-mentioned embodiments, a wiring boardadvantageous in the fine wiring formation, electric properties, andproduction cost can be obtained and a wiring board excellent in highfrequency properties can be obtained as well.

Further, embodiments of the invention are following (1C) to (16C).

-   (1C) A formation method of a resin layer on a metal by forming a    thin film of a polyamide imide on the metal as adhesion promoting    treatment and then coating the metal with the resin.-   (2C) The formation method of a resin layer on a metal according to    (1C), wherein the thickness of the polyamide imide layer is 0.1 to 5    μm.-   (3C) The formation method of a resin layer on a metal according to    (1C) or (2C), wherein the metal is copper.-   (4C) The formation method of a resin layer on a metal according to    one of (1C) to (3C), wherein the polyamide imide layer is formed    directly on copper without any practical surface roughening    treatment.-   (5C) An inner conductor circuit treatment method involving forming a    polyamide imide layer as an adhesion promoting agent on a core    substrate bearing a conductor circuit.-   (6C) The inner conductor circuit treatment method according to (5C),    wherein the thickness of the polyamide imide layer is 0.1 to 5 μm.-   (7C) The inner conductor circuit treatment method according to (5C)    or (6C), wherein the polyamide imide layer is formed by immersing    the core substrate bearing the conductor circuit in a polyamide    imide solution.-   (8C) The inner conductor circuit treatment method according to (7C),    wherein after immersion to the polyamide imide solution, the    polyamide imide is set in B stage state by drying until the    remaining solvent is decreased to 1% or less.-   (9C) The inner conductor circuit treatment method according to one    of (5C) to (8C), wherein the conductor circuit is made of copper and    the polyamide imide layer is formed directly on the copper without    any practical surface-roughening treatment.-   (10C) The inner conductor circuit treatment method according to one    of (5C) to (9C), wherein the conductor circuit has ten-point mean    surface roughness (Rz) of 2.0 μm or less.-   (11C) The inner conductor circuit treatment method according to one    of (5C) to (10C), wherein the insulating layer contained in the core    substrate has ten-point mean surface roughness (Rz) of 2.0 μm or    less.-   (12C) The inner conductor circuit treatment method according to one    of (5C) to (11C), wherein a polyamide imide provided with high    moisture absorbing and heat resistant properties by comprising a    saturated hydrocarbon as a unit component is used.-   (13C) The inner conductor circuit treatment method according to one    of (5C) to (12C) involving forming an insulating layer on the core    substrate subjected to the inner conductor circuit treatment.-   (14C) The inner conductor circuit treatment method according to    (13C), wherein the insulating layer contains at least an epoxy    resin.-   (15C) The inner conductor circuit treatment method according to one    of (13C) or (14C), wherein the insulating layer is made of prepreg.-   (16C) A multilayer wiring board comprising wiring, a polyamide imide    resin layer and an insulating layer, wherein the wiring is inside of    the multilayer wiring board, the insulating layer is an outer layer    which contacts the wiring via the polyamide imide resin layer.

According to the embodiments, an inner conductor circuit treatmentmethod capable of providing excellent electric properties andsuppressing dispersion of wiring and occurrence of defection isprovided.

The present disclosure relates to subject matter contained in JapanesePatent Application No. 2003-385852 filed on Nov. 14, 2003, No.2003-385853 filed on Nov. 14, 2003, No. 2004-018139 filed on Jan. 27,2004, No. 2004-024400 filed on Jan. 30, 2004, No. 2004-024422 filed onJan. 30, 2004, the disclosure of which is expressly incorporated hereinby reference in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional view showing one embodiment of printedwiring board production process according to the invention.

FIG. 2 shows a cross-sectional view showing another embodiment ofprinted wiring board production process according to the invention.

FIG. 3 shows a cross-sectional view showing another embodiment ofprinted wiring board production process according to the invention.

FIG. 4 illustrates an evaluation method of gold plating precipitationamount on a resin.

FIG. 5 shows a cross-sectional view of a substrate for connectionreliability evaluation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the embodiments of the invention will be described indetail with reference to drawings.

At first, a core substrate comprising two layers is produced. In thecase of producing the core substrate, metal layers 2 and 202 are formedin both sides 1 and 201 of an insulating layer as shown in FIG. 1( a)and FIG. 3( a). For example, a method of using a laminate platecomprising metal foils on both sides of a prepreg is economical andtherefore preferable.

As shown in FIG. 2( a), an adhesive layer 103 may be inserted betweenthe insulating layer 101 and the metal layer 102 for improving theadhesion. The adhesive layer 103 is only an intermediate for improvingthe adhesion to the metal foils. The thickness of the adhesive layer ispreferably 0.1 μm or thicker in terms of the adhesion. Also, thethickness of the adhesive layer is preferably 10 μm or thinner inconsideration of the connection reliability. The thickness is furtherpreferably 0.1 to 5 μm, even more preferably 0.5 to 2.0 μm. Thethickness of the adhesive layer is desirable to be ⅛ or thinner than thethickness of the insulating layer in terms of the reliability andelectric properties. A composite material of an inorganic substance andan organic substance is preferable for the insulating layer and aprepreg is preferable to use for lowering the cost.

The prepreg is produced by immersing or coating a substrate with a resincomposition. As the substrate, various types of well known substratesused for laminate plates for electric insulating materials may be used.Examples of the materials for the substrate are inorganic fibers of suchas E glass, D glass, S glass or Q glass; organic fibers of such aspolyimides, polyesters, or tetrafluoroethylene; and their mixtures,however the materials are not limited to these examples.

These substrates may be in any form such as woven fabrics, nonwovenfabrics, roving, chopped strand mats, surfacing mats and the like. Thematerials and the forms of the substrate may be selected properlydepending on the uses and functions of the aimed formed products.Further, if necessary, those made of one or more kinds of materials andhaving one or more forms may be used. The thickness of the substrate isnot particularly limited, however those with a thickness of about 0.03to 0.5 mm may be used in general. Those subjected to surface-treatmentwith a silane coupling agent or the like or to mechanical fibrillationare preferable in terms of the heat resistance, moisture resistance, andprocessibility.

As a resin composition, conventionally known resin compositions to beused as insulating materials for a printed wiring board may be used.Generally, a thermosetting resin excellent in heat resistance andchemical resistance may be used as a base. Examples of the thermosettingresin are phenol resins, epoxy resins, cyanate resins, maleimide resins,isocyanate resins, benzocyclobutene resins, and vinyl resins, howeverthe thermosetting resin is not limited to these examples. As thethermosetting resin, one kind of resins may be used alone or two kindsof resins may be mixed and used.

Among the thermosetting resins, the epoxy resins are widely used sincethey are excellent in heat resistance, chemical resistance, and electricproperties and relatively economical. Examples of the epoxy resins arebisphenol type epoxy resins such as bisphenol A type epoxy resin,bisphenol F type epoxy resin, and bisphenol S type epoxy resin; novolaktype epoxy resins such as phenol novolak type epoxy resin, cresolnovolak type epoxy resin, and bisphenol A novolak type epoxy resin;alicyclic epoxy resins; aliphatic chain epoxy resins; diglycidyl ethercompounds of bisphenol; diglycidyl ether compounds of naphthalene diol;diglycidyl ether compounds of phenol; diglycidyl ether compounds ofalcohols; and their alkyl-substituted compounds, halogenated compounds,and hydrogenated compounds, however the epoxy resins are not limited tothese examples. One kind of the epoxy resins may be used alone or two ormore kinds of the epoxy resins may be mixed and used. As a curing agentto be used together with the epoxy resins, any agents may be usedwithout particular limit if they can cure the epoxy resins. Examples ofthe curing agents are polyfunctional phenols, polyfunctional alcohols,amines, imidazole compounds, acid anhydrides, organic phosphoruscompounds and their halides, however the curing agents are not limitedto these examples. One kind of these epoxy resin curing agents may beused alone or two or more kinds may be mixed and used.

The cyanate ester resin is a thermosetting resin comprising triazinerings as repeating units and obtained by heating a cyanate compound. Theresin is used in the case excellent high frequency properties arerequired since the resin is excellent in the dielectric properties.Examples of the cyanate compound are cyanate ester compounds such as2,2-bis(4-cyanatophenyl)propane, bis(4-cyanatophenyl)ethane,2,2-bis(3,5-dimethyl-4-cyanatophenyl)methane,2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane, α,α′-bis(4-cyanatophenyl)-m-diisopropylbenzene, phenol novolak, andalkylphenol novolak, however the cyanate compound may not be limitedparticularly to these examples. Among them,2,2-bis(4-cyanatophenyl)propane is preferable since it is excellent inthe balance of the dielectric property of a cured product and curingproperty and is economically in terms of the cost. One kind of cyanateester compounds may be used alone or two or more kinds may be mixed andused. The cyanate ester compound to be used here may be oligomeratedpartially into trimers and pentamers. A curing catalyst and a curingpromoter may be added to the cyanate compound for curing. Examples ofthe curing catalyst may be metals such as manganese, iron, cobalt,nickel, copper, zinc and the like, however the catalyst may not belimited to these examples. Practical examples are organometal salts suchas 2-ethylhexanates, naphthanates, and octylates; and organometalcomplexes such as acetylacetone complexes, however the catalyst may notbe limited to these examples. They may be use alone or two or more kindsof them may be mixed and used. Phenols are used preferably as the curingpromoter. Practically, examples are monofunctional phenols such asnonylphenyl and p-cumylphenyl; bifunctional phenols such as bisphenol A,bisphenol F, and bisphenol S; and polyfunctional phenol such as phenolnovolak and cresol novolak, however it is not limited to these examples.They may be used alone or two or more kinds of them may be mixed andused.

In consideration of the dielectric properties, impact resistance, andfilm formability, the resin composition may be blended with athermoplastic resin. Examples of the thermoplastic resin are fluororesins, polyphenylene ethers, modified polyphenylene ethers,polyphenylene sulfides, polycarbonates, polyether imides, polyetherether ketones, polyallylates, polyamides, polyamide imides,polybutadienes, however the thermoplastic resin is not limited to theseexamples. The thermoplastic resins may be used alone or two or moretypes of them may be mixed and used.

The resin composition is preferable to have a specific dielectricconstant 3.0 or lower or a dielectric dissipation factor 0.01 or lowerat 1 GHz. Use of such a resin composition lowers the dielectric loss inwiring and makes it possible to form a circuit with a further loweredtransmission loss. As a resin excellent in such dielectric properties,polyphenylene ethers and cyanate esters may be exemplified. In the caseof using the polyphenylene esters for wiring board materials, it isrequired to add a thermosetting property to improve the heat resistanceand the chemical resistance. For example, thermosetting resins such asepoxy resins, cyanate ester resins, triazine-bismaleimide resins may beblended with the polyphenylene ethers. Or, double bonds or polymerizablefunctional groups such as epoxy group may be introduced into themolecular chains of the polyphenylene ethers.

Among the thermoplastic resins, in the case of adding polyphenyleneethers and modified polyphenylene ethers, the dielectric properties ofcured materials are improved and therefore they are useful. Examples ofthe polyphenylene ethers and modified polyphenylene ethers arepoly(2,6-dimethyl-1,4-phenylene) ether, alloyed polymers ofpoly(2,6-dimethyl-1,4-phenylene) ether and polystyrene, alloyed polymersof poly(2,6-dimethyl-1,4-phenylene) ether and styrene-butadienecopolymers, alloyed polymers of poly(2,6-dimethyl-1,4-phenylene) etherand styrene-maleic anhydride copolymers, alloyed polymers ofpoly(2,6-dimethyl-1,4-phenylene) ether and polyamides, and alloyedpolymers of poly(2,6-dimethyl-1,4-phenylene) ether andstyrene-butadiene-acrylonitrile copolymers, however they are not limitedto these examples. Further, to provide reactivity and polymerizabilityto the polyphenylene ethers, functional groups such as amino, epoxygroup, carboxyl, styryl, and methacryl may be introduced into polymerterminals or functional groups such as amino, epoxy group, carboxyl,styryl, and methacryl may be introduced into the polymer side chains.

Among the thermoplastic resins, polyamide imide resins are excellent inheat resistance, and moisture resistance and therefore useful. Rawmaterials of the polyamide imide resins include acidic components andamine components. Examples of the acid components are trimelliticanhydride and trimellitic anhydride monochloride, however the componentsare not limited to these examples. Examples of the amine components arem-phenylenediamine, p-phenylenediamine, 4,4′-diaminodiphenyl ether,4,4′-diaminodiphenylmethane, bis[4-(aminophenoxy)phenyl]sulfone,2,2′-bis[4-(4-aminophenoxy)phenyl]propane, however the amine componentsare not limited to these examples. To improve the drying property,polyimide amide resins may be modified with siloxane. In such as case,siloxane diamine is used as the amino components. In consideration ofthe processibility, it is preferable to use polyimide amide resinshaving a molecular weight of 50,000 or more. The polyimide amide resinsmay be described more in details later.

The resin composition may contain an inorganic filler.

Examples of the inorganic filler are alumina, aluminum hydroxide,magnesium hydroxide, clay, talc, antimony trioxide, antimony pentoxide,zinc oxide, fused silica, glass powder, quartz powder, and shirasuballoon, however the inorganic filler may not be limited to theexamples. These inorganic fillers may be used alone and two or more ofthem may be mixed and used.

The resin composition may contain an organic solvent. Examples of theorganic solvent are aromatic hydrocarbons solvents such as benzene,toluene, xylene, and trimethylbenzene; ketone type solvents methyl ethylketone and methyl isobutyl ketone; ether type solvents such astetrahydrofuran; alcohol type solvents such as isopropanol and butanol;ether alcohol type solvents such as 2-methoxyethanol, and2-butoxyethanol; and amido type solvents such as N-methylpyrrolidone,N,N-dimethylformamide, and N, N-dimethylacetamide, however the organicsolvent may not be limited to these examples and these solvents may beused properly in combination. The solvent amount in a varnish in thecase of producing a prepreg is preferably in a range of 40 to 80% byweight and the viscosity of the varnish is preferably in a range of 20to 100 cP.

The resin composition may contain a flame retardant. Examples to be usedas the flame retardant are conventionally known flame retardants such asbromo compounds such as decabromodiphenyl ether, tetrabromobisphenol A,tetrabromophthalic anhydride, and tribromophenol; phosphorus compoundssuch as triphenyl phosphate, tricresyl phosphate, trixylyl phosphate,cresyldiphenyl phosphate; metal hydroxides such as magnesium hydroxideand aluminum hydroxide; red phosphorus and its modified products;antimony compounds such as antimony trioxide and antimony pentoxide; andtriazine compounds such as melamine, cyanuric acid, melamine cyanurate,however the flame retardant is not limited to these examples.

Further, based on the necessity, various kinds of additives and fillerssuch as a curing agent, a curing promoting agent, thermoplasticparticles, a coloring agent, a UV impermeable agent, an antioxidant, anda reducing agent may be added to the resin composition in theproduction.

In general, the substrate is impregnated in or coated with the resincomposition in an adhesion amount of the composition to the substrateadjusted so as to be 20 to 90% by weight on the basis of resin contentin the prepreg after drying and then the resin composition is driedgenerally at 100 to 200° C. for 1 to 30 minutes to obtain a prepreg insemi-cured state (in B stage state). One to twenty sheets of suchprepreg are laminated; an adhesive is applied to both faces of thelaminate; metal foils are attached to both faces and then the entirebody of the resulting laminate is pressurized while being heated.Conventional laminate plate production technique may be employed for theforming conditions. For example, multi-step pressing, multi-press vacuumpressing, continuous forming, autoclave formation apparatus may be usedfor the formation. The formation may be carried out in conditions of 100to 250° C. temperature, 2 to 100 kg/cm² pressure, and 0.1 to 5 hourheating. Also, using a vacuum lamination apparatus, the formation may becarried out in laminating conditions of 50 to 150° C. temperature and0.1 to 5 MPa vacuum or atmospheric pressure. The thickness of theprepreg layer to be an insulating layer may differ depending on theuses, however it is generally preferably 0.1 to 5.0 mm.

It is preferable to use an insulating layer having a thermal expansioncoefficient of 20 ppm/° C. or lower in the transverse direction (CTE X,CTE Y) in a range of 0 to 150° C. in terms of the improvement ofreliability. Further, a resin having a tensile strength of 200 MPa orhigher at 20° C. is preferable. GEA-E-679F and GEA-679-FG (trade names;manufactured by Hitachi Chemical Co., Ltd.), which are prepreg, may beused for the insulating layer.

Generally, a electrodeposition layer having many very small bumps(so-called Yake plating) is formed on the metal foils or the metal foilsare subjected to roughening treatment by oxidation, reduction, oretching. Japanese Patent Application Laid-Open No. 8-21618 disclosessubstances for the above-mentioned electrodeposition and therefore, theinvention include its specification as reference in this specification.However, the metal foils to be used in the invention are not subjectedto the roughening treatment. Both faces of the metal foils to be usedfor the invention have 2.0 μm or less ten-point mean surface roughness(Rz) defined in JIS B 0601. If no roughening treatment is carried out,the unevenness of the metal foils is slight. Therefore, it isadvantageous since the metal foils do not remain when the metal foilsformed on the resin layer are removed by etching. Copper foils, nickelfoils, and aluminum foils may be used as the metal foils and generally,copper foils are used. The production conditions of the copper foils arecommonly sulfuric acid 50 to 100 g/L, copper 30 to 100 g/L, solutiontemperature 20 to 80° C., and current density 0.5 to 100 A/dm² in thecase of a copper sulfate bath and potassium pyrophosphate 100 to 700g/L, copper 10 to 50 g/L, solution temperature 30 to 60° C., pH 8 to 12,and current density 1 to 10 A/dm² in the case of a copper pyrophosphatebath. Various kinds of additives may be added in consideration of thephysical properties and smoothness of copper.

Further, the foils to be used preferably are peelable type metal foilswith a thickness of 0.3 μm or thinner and a surface roughness Rz of 2.0μm or less. The peelable type metal foils are those having a carrier andthe carrier is separable. For example, in the case of peelable typeultra thin copper foils, a metal oxide or an organic layer to be apeeling layer is formed on a carrier foil with a thickness of 10 to 50μm and metal foils may be formed under the conditions of sulfuric acid50 to 100 g/L, copper 30 to 100 g/L, solution temperature 20 to 80° C.,and current density 0.5 to 100 A/dm² in the case of a copper sulfatebath. Also, the metal foils with a thickness of 0.3 to 3.0 μm may beformed under the conditions of potassium pyrophosphate 100 to 700 g/L,copper 10 to 50 g/L, solution temperature 30 to 60° C., pH 8 to 12, andcurrent density 1 to 10 A/dm² in the case of a copper pyrophosphatebath. In the case of using such foils as electric power supply layers,the wiring formability is excellent as it will be described later. Inplace of the peelable type foils, etchable type copper foils having analuminum carrier or a nickel carrier may be used.

The anti-rust treatment for the faces of the metal foils to be stuck toa resin may be carried out by using nickel, tin, zinc, chromium,molybdenum, cobalt or their alloys. Thin film formation on the metalfoils is carried out by using the metal or alloys by sputtering,electroplating, or electroless plating. Among them, in terms of thecost, electroplating is preferable. Practically, plating is carried outby using a plating solution containing one or more salts of theabove-exemplified metals to form the plating layer. A complexing agentsuch as a citric acid salt, tartaric acid salt, sulfamic acid may beadded to make metal ion precipitation easy. The plating solution isgenerally used in an acidic region and plating is carried out at a roomtemperature to 80° C. Generally, the plating is carried out under theconditions properly selected form 0.1 to 10 A/dm² for the currentdensity and 1 to 60 seconds, preferably 1 to 30 seconds for the currentapplication period. The deposition amount of the anti-rust treatmentmetal differs depending on the metal type, however it is preferably 10to 2,000 μg/dm² in total. If the thickness of the anti-rust treatment istoo thick, it results in etching inhibition and electric propertydeterioration and if the thickness is too thin, it results in decreaseof the peel strength to the resin.

In the case of containing a cyanate resin in the resin composition,nickel is preferable to be used as a main component for the anti-rusttreatment for the metal foils. In this combination, the peel strengthdecrease is slight in a heat resistance deterioration test and amoisture resistance deterioration test and therefore, it isadvantageous.

Further, if a chromate treatment layer is formed on the anti-rusttreatment layer, decrease of the peel strength to the resin issuppressed and therefore, it is advantageous. Practically, the treatmentis carried out by using an aqueous solution containing hexavalentchromium ion. The chromate treatment can be carried out by simpledipping treatment, however cathode treatment is carried out preferably.The treatment may be carried out preferably under the conditions ofsodium dichromate 0.1 to 50 g/L, pH 1 to 13, bath temperature 0 to 60°C., current density 0.1 to 5 A/dm², and electrolytic period 0.1 to 100seconds. Chromic acid or potassium dichromate may be used in place ofsodium dichromate.

In the invention, it is preferable that a silane coupling agent isadsorbed in the outermost layers of the metal foils.

Examples of the silane coupling agent are epoxy functional silanes suchas 3-glycidoxypropyltrimethoxysilane and2-(3,4-epoxycyclohexylethyltrimethoxysilane; amino functional silanessuch as 3-aminopropyltrimethoxysilane,N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, andN-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane; olefin functionalsilanes such as vinyltrimethoxysilane, vinylphenyltrimethoxysilane, andvinyltris(2-methoxyethoxy)silane; acrylic functional silanes such as3-acryloxypropyltrimethoxysilane; methacrylic functional silanes such as3-methacryloxypropyltrimethoxysilane; and mercapto functional silanessuch as 3-mercaptopropyltrimethoxysilane. They may be used alone or aplurality of the silanes may be mixed and used. These coupling agentsmay be dissolved in a solvent in a concentration of 0.1 to 15 g/L andapplied to the metal foils at a room temperature to 50° C. orelectrodeposited for the adsorption. These silane coupling agents form acoating by forming condensation bonding with the hydroxyl groups of theanti-rust metal on the metal foil surface. Stable bonds can be formed byheating or UR radiation after the silane coupling agent treatment. Inthe case of heating, the silane coupling treatment is dried at 100 to200° C. for 2 to 60 second. In the case of UV radiation, the radiationis carried out with 200 to 400 nm wavelength and 200 to 2,500 mJ/cm²intensity.

The combination of the silane coupling agent with the insulating layeror an adhesive layer is preferably selected so as to cause chemicalreaction of the functional groups of the insulating layer or theadhesive layer with the functional groups of the silane coupling agent.For example, in the case epoxy groups are contained in the insulatinglayer or the adhesive layer, if an amino functional silane is selectedas the silane coupling agent, the effect is more efficiently exhibited.It is attributed to that firm chemical bonds are formed between theepoxy groups and amino groups and the bonds are extremely stable to theheat and water. As combinations to form such chemical bonds, epoxygroup-amino group; epoxy group-epoxy group; epoxy group-mercapto group;epoxy group-hydroxyl group; epoxy group-carboxyl group; epoxygroup-cyanato group; amino group-hydroxyl group; amino group-carboxylgroup; and amino group-cyanato group can be exemplified.

In the case the insulating layer or the adhesive layer contains an epoxyresin which is liquid at a normal temperature, the viscosity isconsiderably decreased at the time of melting. Therefore, thewettability in the adhesion interface is improved and the chemicalreaction of the epoxy resin and the coupling agent is easily caused. Asa result, a high peel strength can be obtained. Practically, bisphenol Atype epoxy resin, bisphenol F type epoxy resin, and phenol novolak typeepoxy resin with about 200 epoxy equivalent are preferable.

In the case the insulating layer or the adhesive layer contains ahardening agent, as the hardening agent, a heat curable latent curingagent is preferably used. That is, in the case chemical reaction iscaused between the functional groups of the thermosetting resin and thefunctional groups of the silane coupling agent, it is preferable toselect the curing agent so as to make the reaction temperature of thefunctional groups of the thermosetting resin and the functional groupsof the silane coupling agent lower than the temperature at which thecuring reaction of the thermosetting resin. Accordingly, the reaction ofthe functional groups of the thermosetting resin and the functionalgroups of the silane coupling agent is carried out in higher priorityand selectively. Therefore, the adhesion of the metal foils and theresin composition is increased. As the thermosetting type latent curingagent for the resin composition containing the epoxy resin, soliddispersion-heat dissolution type curing agents of such as dicyandiamine,dihydrazide compounds, imidazole compounds, and amine-epoxy adducts andreactive group block type curing agents of such as urea compounds, oniumcompounds, boron trichloride-amine salts, block carboxylic acidcompounds can be exemplified.

If a polyamide imide type resin is contained in the insulating layer oradhesive layer, especially high adhesion can be obtained. Since thepolyamide imide resin type adhesive shows high adhesion to a copper foilwhich is not subjected to the anti-rust treatment or coupling agenttreatment, these treatments may be eliminated.

As a production method of the polyamide imide, an isocyanate methodbased on the reaction of trimellitic anhydride and an aromaticdiisocyanate is available. Application examples of the method are amethod (U.S. Pat. No. 2,897,186) involving reaction of an aromatictricarboxylic acid anhydride and a diamine having ether bond in excessdiamine condition and then reaction with diisocyanate and a method(Japanese Patent Application Laid-Open No. 04-182466) involving reactionof an aromatic diamine and trimellitic anhydride.

It is also possible to improve the properties such as the modulus ofelasticity, flexibility, and drying efficiency by introducing siloxanestructure into the polyamide imide. The polyamide imide can be producedaccording to the isocyanate method and for example, a method (JapanesePatent Application Laid-Open No. 05-009254) involving condensationpolymerization of an aromatic tricarboxylic acid anhydride, an aromaticdiisocyanate, and siloxanediamine; a method (Japanese Patent ApplicationLaid-Open No. 6-116517) involving condensation polymerization of anaromatic dicarboxylic acid or an aromatic tricarboxylic acid withsiloxanediamine; and a method (Japanese Patent Application Laid-Open No.11-130831) involving reaction of an aromatic diisocyanate with a mixturecontaining a diamide dicarboxylic acid obtained by reaction oftrimellitic acid and a mixture containing a diamine having 3 or morearomatic rings and siloxanediamine can be exemplified. The polyamideimide type adhesive layer is used while being mixed with a thermosettingepoxy resin-containing resin composition based on necessity. Thedisclosure of the U.S. Pat. No. 2,897,186, Japanese Patent ApplicationLaid-Open Nos. 04-182466, 05-009254, 06-116517, and 11-130831 isexpressly incorporated herein by reference in its entirety.

The resin composition as described above and metal foils which are notsubjected to the surface roughening treatment are laminated and unitedby a conventionally known method to obtain a laminate plate shown inFIG. 1( a) and FIG. 3( a). The adhesive and the metal foils which arenot subjected to the surface roughening treatment are printed by aconventional method and after that the foils are laminated on theinsulating layers to obtain the laminate plate shown in FIG. 2( a).

Next, penetrating through holes 4, 104, and 204 for interlayerconnection are formed in the above-mentioned laminate body (FIG. 1( b),FIG. 2( b), and FIG. 3( b)). If the through hole diameter is 100 μm orwider, drilling work is suitable. If the through hole diameter is 100 μmor narrower, gas laser of CO₂, CO, and excimer laser, and solid lasersuch as YAG laser are suitable to be employed. If the through holediameter is around 100 μm, either method may be used.

Next, a catalyst core is supplied to the metal foils and the IVHinsides. To supply the catalyst core, a noble metal ion or palladiumcolloid is used. Practically, Activator Neoganth (trade name,manufactured by Atotech Japan K.K.), a palladium ion catalyst, and HS201B (trade name, manufactured by Hitachi Chemical Co., Ltd.), apalladium colloid catalyst can be used. In the case of supplying thepalladium catalyst, conditioning treatment with such as CLC-201 (tradename, manufactured by Hitachi Chemical Co., Ltd.) is previously carriedout.

Next, as shown in FIG. 1( c), FIG. 2( c), and FIG. 3( c), thinelectroless plating layers 5, 105, and 205 are formed on the metal foilsand IVH insides to which the catalyst core is supplied. For theelectroless plating, commercialized electroless copper plating solutionssuch as CUST 2000 (trade name, manufactured by Hitachi Chemical Co.,Ltd.) and CUST 201 (trade name, manufactured by Hitachi Chemical Co.,Ltd.) can be employed, however the plating is not limited to theexamples. These electroless copper plating solutions contain mainlycopper sulfate, formalin, a complexing agent, and sodium hydroxide. Thethickness of the plating is sufficient if the next electroplating can becarried out thereon and it is about 0.1 to 1 μm.

Next, as shown in FIG. 1( d), FIG. 2( d), and FIG. 3( d), plating resist6, 106, and 206 is formed on the electroless plating layers. Thethickness of the plating resist is preferably as same as or thicker thanthe thickness of a conductor for planting thereafter. Examples of theresin to be used for the plating resist are liquid phase resist such asPMER P-LA900PM (trade name; manufactured by Tokyo Ohka Kogyo Co., Ltd.),and dry films such as HW-425 (trade name, manufactured by HitachiChemical Co., Ltd.) and RY-3025 (trade name, manufactured by HitachiChemical Co., Ltd.). The plating resist should not be formed on theportions to be via holes and a conductor circuit.

Next, as shown in FIG. 1( e), FIG. 2( e), and FIG. 3( e), circuitpatterns 7, 107, and 207 are formed by electroplating. A copper sulfateelectroplating to be used commonly for a printed wiring board may beused. The thickness of the plating is sufficient if it is used as acircuit conductor and preferably in a range of 1 to 100 μm, morepreferably in a range of 5 to 50 μm.

Next, as shown in FIG. 1( f), FIG. 2( f), and FIG. 3( f), resist isseparated and the metal other than the pattern parts is removed. As aresist separation solution, alkaline separation solutions, sulfuricacid, and commercialized resist separation solutions may be employed. Asthe metal other than the pattern parts, for example copper is removed byetching. In this case etching is generally carried out by high pressurespraying or the like. However, the solution exchange is deterioratedinevitably in the portions where the wiring is made fine. Accordingly,the reaction of the copper and the etching solution is desirably carriedout based on the reaction speed but not on the diffusion speed. If thereaction of copper and the etching solution is carried out based on thereaction speed, even if the diffusion is more increased, the etchingspeed is not changed. That is, no etching speed difference is causedbetween the portions where the solution exchange is well promoted andthe portions where the solution exchange is poorly promoted.Practically, an etching solution containing hydrogen peroxide and ahalogen element-free acid as main components is preferably used. Ifhydrogen peroxide is used as an oxidizing agent, strict etching speedcontrol is made possible by controlling the hydrogen peroxideconcentration. Additionally, if a halogen element is added to theetching solution, the dissolution reaction tends to be promoteddepending on the diffusion speed. As the halogen-free acid, nitric acid,sulfuric acid, and organic acids are usable and sulfuric acid iseconomical and therefore preferable. In the case the etching solutioncontains sulfuric acid and hydrogen peroxide as main components, theirconcentrations are preferable to be 5 to 300 g/L and 5 to 200 g/L,respectively, in terms of the etching speed and the stability of thesolution.

According to the method described above, a core substrate composed oftwo layers is completed. Further, in the case of producing a four-layerplate, the inner conductor circuits on the surface of the core substrateare surface-roughened to improve the close adhesion to the interlayerresin insulating layers to be formed on the copper patterns.Practically, a method of forming needle-like electroless plating layerson the core substrate, a method of oxidizing (blackening)-reducing theinner copper patterns, and a method of etching the inner copper patternsare available. However, since these methods require the inner conductorcircuits to be surface-roughened, a method which does not include asurface-roughening step as described below is more preferable. That is,as shown in FIG. 2( g) and FIG. 3( g), the entire conductor circuits arepreferable to be covered with polyamide imide as an adhesion promotingagent 108,208. Accordingly, even if copper foils which are not treatedare provided with high adhesion property. To improve the adhesion, thatis, as the adhesion promoting agent, the thickness of the polyamideimide layer is preferably 0.1 to 10 μm and more preferably 0.1 to 5 μm.If the thickness of the polyamide imide layer is thinner than 0.1 μm,the adhesion property is insufficient and if it is thicker than 10 μm,the respective properties such as elongation, dielectric constant, anddielectric dissipation factor are affected inversely in some cases.

The conductor circuit surface may be subjected to anti-rust treatmentwith nickel, tin, zinc or palladium or surface-roughening treatment.Accordingly, not only high adhesion is provided but also the anti-rusttreatment degree or the surface-treatment degree can be decreased insome cases. That is, the invention may be combined with a conventionallyknown method.

By the above-mentioned method, sufficiently high adhesion strength canbe obtained. To obtain further high adhesion strength, a polyimide amidecomprising saturated hydrocarbon repeating unit is preferable. It isalso more preferable to contain an alicyclic hydrocarbon group in therepeating unit. Existence of the alicyclic hydrocarbon group providesmoisture absorbing property and heat resistance to the polyamide imideand also a high Tg. Use of such a polyamide imide improves thereliability.

The saturated hydrocarbon component comprising the alicyclic hydrocarbongroup may be derived from a diamine compound comprising a saturatedhydrocarbon having an alicyclic hydrocarbon group as a raw material.

Such a diamine is defined by the following general formula (1a) or (1b).

In the formula, X¹ represents an aliphatic hydrocarbon group having 1 to3 carbon atoms, a halo aliphatic hydrocarbon group having 1 to 3 carbonatoms, sulfonyl, an ether group, carbonyl, a single bond, or a divalentgroup defined by the following general formula (2a) or (2b); Y¹represents an aliphatic hydrocarbon group having 1 to 3 carbon atoms, ahalo aliphatic hydrocarbon group having 1 to 3 carbon atoms, sulfonyl,an ether group, or carbonyl; R¹, R², and R³ may be same or differentfrom one another and independently represent a hydrogen atom, hydroxyl,methoxy group, methyl, or a halo methyl:

wherein Z¹ represents an aliphatic hydrocarbon group having 1 to 3carbon atoms, a halo aliphatic hydrocarbon group having 1 to 3 carbonatoms, sulfonyl, an ether group, carbonyl, or a single bond.

Examples of the diamine compound comprising a saturated hydrocarbonhaving an alicyclic hydrocarbon group are2,2-bis[4-(4-aminocyclohexyloxy)cyclohexyl]propane,bis[4-(3-aminocyclohexyloxy)cyclohexyl]sulfone,bis[4-(4-aminocyclohexyloxy)cyclohexyl]sulfone,2,2-bis[4-(4-aminocyclohexyloxy)cyclohexyl]hexafluoropropane,bis[4-(4-aminocyclohexyloxy)cyclohexyl]methane,4,4′-bis(4-aminocyclohexyloxy)dicyclohexyl,bis[4-(4-aminocyclohexyloxy)cyclohexyl]ether,bis[4-(4-aminocyclohexyloxy)cyclohexyl]ketone,1,3-bis(4-aminocyclohexyloxy)benzene,1,4-bis(4-aminocyclohexyloxy)benzene,2,2′-dimethylbicyclohexyl-4,4′-diamine,2,2′-bis(trifluoromethyl)dicyclohexyl-4,4′-diamine,2,6,2′,6′-tetramethyl-4,4′-diamine,5,5′-dimethyl-2,2′-sulfonyl-dicyclohexyl-4,4′-diamine,3,3′-dihydroxydicyclohexyl-4,4′-diamine, (4,4′-diamino)dicyclohexylether, (4,4′-diamino)dicyclohexylsulfone,(4,4′-diaminocyclohexyl)ketone, (3,3′-diamino)benzophenone,(4,4′-diamino)dicyclohexylmethane, (4,4′-diamino)dicyclohexyl ether,(3,3′-diamino)dicyclohexyl ether, (4,4′-diamino)dicyclohexylmethane,(3,3′-diamino)dicyclohexyl ether, and 2,2-bis(4-aminocyclohexyl)propane,however the diamine compound is not limited to these examples. Two ormore kinds of these diamine compounds may be mixed and used and further,other diamine compounds may be used in combination.

Such a diamine compound comprising a saturated hydrocarbon having analicyclic hydrocarbon group is easily produced by hydrogen reducing anaromatic diamine compound.

Examples of such an aromatic diamine compound are2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP),bis[4-(3-aminophenoxy)phenyl]sulfone,bis[4-(4-aminophenoxy)phenyl]sulfone,2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,bis[4-(4-aminophenoxy)phenyl]methane, 4,4′-bis(4-aminophenoxy)diphenyl,bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ketone,1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene,2,2′-dimethylbiphenyl-4,4′-diamine,2,2′-bis(trifluoromethyl)diphenyl-4,4′-diamine,2,6,2′,6′-tetramethyl-4,4′-diamine,5,5′-dimethyl-2,2′-sulfonyl-biphenyl-4,4′-diamine,3,3′-dihydroxydiphenyl-4,4′-diamine, (4,4′-diamino)diphenyl ether,(4,4′-diamino)diphenylsulfone, (4,4′-diamino)benzophenone,(3,3′-diamino)benzophenone, (4,4′-diamino)diphenylmethane,(4,4′-diamino)diphenyl ether, and (3,3′-diamino)diphenyl ether, however,the aromatic diamine compound is not limited to these examples.

Hydrogen reduction of the aromatic diamine compound is carried out by ageneral reduction method of an aromatic ring. Practically, examples ofthe method are methods using catalyst systems such as Raney Nikkel andplatinum oxide in the presence of hydrogen (D. Varech et al, TetrahedronLetter 26, 61 (1985); R. H. Baker et al, J. Am. Chem. Soc., 69, 1250(1947)); rhodium-aluminum oxide (J. C. Sircar et al, J. Org. Chem., 30,3206 (1965); A. I. Meyers et al, Organic Synthesis Collective Volume VI,371 (1988); A. W. Burgstahler, Organic Synthesis Collective Volume V,591 (1973); A. J. Briggs, synthesis, 1988, 66); rhodium oxide-platinumoxide (S. Nishimura, Bull, Chem. Soc. Jpn., 34, 32 (1961); E. J. Coreyet al, J. Am. Chem. Soc. 101, 1608 (1979)); charcoal carrying rhodium(K. Chebaane et al, Bull. Soc. Chim. Fr., 1975, 244) and sodium boronhydride-rhodium chloride system (P. G. Gassman et al, Organic SynthesisCollective Volume VI, 581 (1988); P. G. Gassman et al, Organic SynthesisCollective Volume VI, 601 (1988)), however the method is not limited tothese exemplified methods.

In addition to the above-mentioned diamine compound as the aliphaticdiamine compound, a compound defined by the following general formula(4) may be used in the polyamide imide and its production method of theinvention.

In the formula, X³ represents methylene group, sulfonyl, an ether group,carbonyl, or a single bond; R¹² and R¹³ independently represent ahydrogen atom, an alkyl, phenyl, or a substituted phenyl; and prepresents an integer of 1 to 50.

Practical examples for R¹² and R¹³ are preferably a hydrogen atom, analkyl with 1 to 3 carbon atoms, phenyl, and a substituted phenyl. As thesubstituent group to be bonded to the phenyl, an alkyl with 1 to 3carbon atoms and halogen atoms can be exemplified.

With respect to the aliphatic diamine defined by the above-mentionedgeneral formula (4), X³ in the formula (4) is preferably an ether groupin terms of the low modulus of elasticity and high Tg. Examples of suchan aliphatic diamine are Jeffamine D-400 and Jeffamine D-200manufactured by Huntsman LLC, however it is not limited to theseexamples.

It is supposed that the polyamide imide having the above-mentionedaliphatic structure is provided with extremely high water absorbingability and water-shedding property as compared with a conventionalpolyamide imide. Accordingly, in the case the polyamide imide comprisingthe saturated hydrocarbon containing the alicyclic hydrocarbon group isused for a thermosetting resin composition, which will be describedlater, as the layer formation material of a laminate, the decrease ofthe adhesion strength at the time of absorbing moisture is suppressed ascompared with that in the case of using a polyamide imide compositioncontaining aromatic composition before the hydrogen reduction.

In the polyamide imide and the production method of the invention, inaddition to the above-exemplified diamine compounds as the diaminecompound, an aromatic diamine may further be added.

Examples of such an aromatic diamine compound are those defined by thefollowing general formula (5a) or the following general formula (5b).

In the above-mentioned general formula (5a), X² represents an aliphatichydrocarbon group having 1 to 3 carbon atoms, a halo aliphatichydrocarbon group having 1 to 3 carbon atoms, sulfonyl, an ether group,carbonyl, a single bond, or a divalent group defined by the followinggeneral formula (6a) or (6b); R¹⁴, R¹⁵, and R¹⁶ may be same or differentfrom one another and independently represent a hydrogen atom, hydroxyl,methoxy group, methyl, or a halo methyl: and in the above-mentionedgeneral formula (5b), Y² represents an aliphatic hydrocarbon grouphaving 1 to 3 carbon atoms, a halo aliphatic hydrocarbon group having 1to 3 carbon atoms, sulfonyl, an ether group, or carbonyl;

wherein Z represents an aliphatic hydrocarbon group having 1 to 3 carbonatoms, a halo aliphatic hydrocarbon group having 1 to 3 carbon atoms,sulfonyl, an ether group, carbonyl, or a single bond.

As the above-mentioned aromatic diamine, compounds comprising aromaticring system to which two amino groups are directly bonded and diaminesto which two or more aromatic rings are directly or through onefunctional group bonded can be exemplified without any particular limit.Practical examples of the diamine are2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP),bis[4-(3-aminophenoxy)phenyl]sulfone,bis[4-(4-aminophenoxy)phenyl]sulfone,2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,bis[4-(4-aminophenoxy)phenyl]methane, 4,4′-bis(4-aminophenoxy)diphenyl,bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ketone,1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene,2,2′-dimethylbiphenyl-4,4′-diamine,2,2′-bis(trifluoromethyl)biphenyl-4,4′-diamine,2,6,2′,6′-tetramethyl-4,4′-diamine,5,5′-dimethyl-2,2′-sulfonyl-biphenyl-4,4′-diamine,3,3′-dihydroxydiphenyl-4,4′-diamine, (4,4′-diamino)diphenyl ether,(4,4′-diamino)diphenylsulfone, (4,4′-diaminophenyl)benzophenone,(3,3′-diamino)benzophenone, (4,4′-diamino)diphenylmethane,(4,4′-diamino)diphenyl ether, and (3,3′-diamino)diphenyl ether, however,the aromatic diamine compound is not limited to these examples. Two ofmore kinds of these aromatic diamine compounds may be mixed and used.

Use of the above-mentioned aromatic diamine compounds further increasesTg and improves the heat resistance.

In the polyamide imide and its production method of the invention, inaddition to the above-exemplified diamine compounds as the diaminecompound, a siloxane diamine defined by the general formula (3) may befurther contained.

In the general formula (3), R⁴ to R⁹ independently represent preferablyan alkyl having 1 to 3 carbon atoms, phenyl, or a substituted phenyl. Asthe substituent group of the substituted phenyl, an alkyl having 1 to 3carbon atoms or a halogen atom is preferable. R¹⁰ to R¹¹ independentlyrepresent preferably an alkylene having 1 to 6 carbon atoms or anarylene group. As the arylene group, phenylene, substituted phenylene,naphthalene, or substituted naphthalene is preferable. As thesubstituent group of the substituted arylene, an alkyl having 1 to 3carbon atoms or a halogen atom is preferable. Additionally, R⁴ to R¹¹which respectively exist in plural number may be same or different fromone another. As such a siloxanediamine, dimethylsiloxane-terminateddiamines are particularly preferable. These siloxanediamines may be usedalone or in combinations. Examples of the siloxanediamine defined by theabove-mentioned general formula (3) are Silicone Oil X-22-161AS (amineequivalent 450), X-22-161A (amine equivalent 840), X-22-161B (amineequivalent 1,500), X-22-9409 (amine equivalent 700), X-22-1660B-3 (amineequivalent 2,200) (all exemplified above are manufactured by Shin-EtsuChemical Co., Ltd.), BY16-853 (amine equivalent 650), BY16-853BA (amineequivalent 200), (all exemplified above are manufactured by Dow CorningToray Co., Ltd.) and they are industrially made available, however thesiloxanediamine is not limited to these examples.

In a production method of the polyamide imide, addition of theabove-mentioned siloxanediamine makes the polyamide imide to be obtainedhave the siloxane structure in the main chain. Therefore, theflexibility of the polyamide imide to be obtained can be improved andoccurrence of blister or the like under high temperature condition canremarkably be suppressed.

In the production method of polyamide imide, the amino groups of theabove-mentioned diamine compounds are reacted with carboxyl groups oftrimellitic anhydride or carboxyl anhydride. Among them, reaction withcarboxyl anhydride is preferable. Such a reaction is carried out at 70to 100° C. in a non-proton type polar solvent.

Examples of the non-proton type polar solvent are N-methyl-2-pyrrolidone(NMP), γ-butyrolactone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, sulfolane, and cyclohexanone, however non-proton type polarsolvent is not limited to these examples. One or more of these solventsmay be used, however NMP is preferable to be used.

Such a non-proton type polar solvent is added in an amount so as tocontrol the solid content preferably 10 to 70% by weight, morepreferably 20 to 60% by weight, in the entire weight of the solution. Ifthe solid content concentration in the solution is less than 10% byweight, since the use amount of the solvent is so much, it tends to beindustrially disadvantageous. If it exceeds 70% by weight, thesolubility of trimellitic anhydride is decreased and therefore itbecomes difficult to carry out reaction sufficiently in some cases.

On completion of the above-mentioned reaction, an aromatic hydrocarbonazeotropic with water is added and reaction is further promoted at 150to 200° C. for dehydration ring-closing reaction. Accordingly, an imidogroup-containing dicarboxylic acid can be obtained. Examples of thearomatic hydrocarbon azeotropic with water are toluene, benzene, xyleneand ethylbenzene, however the aromatic hydrocarbon azeotropic with wateris not limited to these examples. Among them, toluene is preferablyused. Such an aromatic hydrocarbon is preferably added in an amount of10 to 50% by weight to the weight of the non-proton polar solvent. Ifthe addition amount of the aromatic hydrocarbon is less than 10% byweight to the weight of the non-proton polar solvent, the water removaleffect tends to be insufficient and the production amount of the imidogroup-containing dicarboxylic acid also tends to be decreased. If itexceeds 50% by weight, the reaction temperature is decreased and theproduction amount of the imido group-containing dicarboxylic acid alsotends to be decreased.

Further, in the dehydration ring-closing reaction, the aromatichydrocarbon is sometimes distilled simultaneously with water, so thatthe aromatic hydrocarbon amount sometimes becomes less than theabove-mentioned preferable range. Therefore, it is preferable to keepthe aromatic hydrocarbon amount constant by separating the aromatichydrocarbon distilled to the plug-equipped water quantitative receiverfrom water and then turning the aromatic hydrocarbon back. On completionof the dehydration ring-closing reaction, it is preferable to keep thetemperature at 150 to 200° C. to remove the aromatic hydrocarbonazeotropic with water.

The imido group-containing dicarboxylic acid to be obtained by theabove-mentioned reaction is preferably the compound defined by thefollowing general formula (7a). In the formula, G represents a residualgroup derived from the diamine defined by the general formulas (1a),(1b), (3), (4), (5a) or (5b) from which the amino group is removed. R¹to R¹⁶ and p, m, and n are same as defined above.

The polyamide imide used in the invention can be produced by inducingthe above-mentioned imido group-containing dicarboxylic acid to acidhalide and polymerizing the acid halide with the above-mentioned diaminecompound.

In such a reaction, the imido group-containing dicarboxylic acid iseasily led to the acid halide by thionyl chloride, phosphorustrichloride, phosphorus pentachloride, or dichloromethyl methyl ether.The imido group-containing dicarboxylic acid halide is easilypolymerized with the above-mentioned diamine compound.

The polyamide imide used in the invention is produced by polymerizingthe above-mentioned imido group-containing dicarboxylic acid with theabove-mentioned diamine compound in the presence of a condensationagent.

In such a reaction, as the condensation agent, common condensationagents for forming amido bond can be used. For the condensation,particularly dicyclohexylcarbodiimide, diisopropylcarbodiimide, orN-ethyl-N′-3-dimethylaminopropylcarbodiimide is preferably used alone orin combination with N-hydroxysuccinimide or 1-hydroxybenzotriazole.

The polyamide imide used in the invention is produced also by convertingthe imido group-containing dicarboxylic acid into the acid halide andcausing reaction of the acid halide with diisocyanate.

In such a reaction, diamine compound:trimellitic anhydride:diisocyanateis preferably in a range of 1:(2 to 2.2):(1 to 1.5) by mole and morepreferably in a range of 1:(2 to 2.2):(1 to 1.3) by mole. A polyamideimide having a high molecular weight and advantageous in the filmformability can be obtained by controlling the mole ratio in theabove-mentioned range.

As the diisocyanate to be employed for the polyamide imide productionmethod of the invention, a compound defined by the general formula (8)can be used.OCN-D-NCO  (8)

In the formula, D represents a divalent organic group having at leastone aromatic ring or a divalent aliphatic hydrocarbon group.Practically, at least one group selected from —C₆H₄—CH₂—C₆H₄, tolylene,naphthylene, hexamethylene, 2,2,4-trimethylhexamethylene, and isophoronegroup is preferable.

As the diisocyanate defined by the above-mentioned general formula (8),an aliphatic diisocyanate or an aromatic diisocyanate may be used.Between them, the aromatic diisocyanate is preferably used andcombination use of both is more preferable.

Examples of the aromatic diisocyanate are 4,4′-diphenylmethanediisocyanate (MDI), 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanate, naphthalene-1,5-diisocyanate, and 2,4-tolylene dimer,however the aromatic diisocyanate is not limited to these examples.Among them, MDI is preferably used. Use of MDI improves the flexibilityof the polyamide imide to be obtained and decreases the crystallinityand accordingly improves the film formability of the polyamide imide.

Examples of the aliphatic diisocyanate are hexamethylene diisocyanate,2,2,4-trimethylhexamethylene diisocyanate, and isophorone diisocyanate,however the aliphatic diisocyanate is not limited to these examples.

In the case the aromatic diisocyanate and the aliphatic diisocyanate areused in combination, the aliphatic diisocyanate is preferably added inan amount of 5 to 10% by mole to the aromatic diisocyanate. Suchcombination use further improves the heat resistance of the polyimideamide to be obtained.

The reaction of the imido group-containing dicarboxylic acid anddiisocyanate is carried out by adding the diisocyanate to a solutioncontaining the imido group-containing dicarboxylic acid obtained by theabove-mentioned reaction and keeping the reaction temperature at 130 to200° C.

In the case of using a basic catalyst, the reaction of the imidogroup-containing dicarboxylic acid and the diisocyanate is carried outpreferably at 70 to 180° C. and more preferably at 120 to 150° C. In thecase of the reaction in the presence of such a basic catalyst, thereaction can be carried out at a lower temperature than that of thereaction to be carried out in the absence of the basic catalyst.Therefore, the side reaction such as reaction of the diisocyanatemolecules themselves can be suppressed and a polyamide imide with afurther higher molecular weight can be obtained.

Examples of such a basic catalyst are trialkylamines such astrimethylamine, triethylamine, tripropylamine, tri(2-ethylhexyl)amine,and trioctylamine. Among them, triethylamine has a preferable basicityfor reaction promotion and is easy to be removed after the reaction andtherefore is preferable.

The polyamide imide to be obtained by the above-mentioned reactioncomprises a repeating unit defined by the following general formula (9).In the formula, G represents a residual group derived from the diaminedefined by the general formulas (1a), (1b), (3), (4), (5a) or (5b) fromwhich the amino group is removed. R¹ to R¹⁶ and p, m, and n are same asdefined above.

The polyamide imide obtained in such a manner as described above has aweight average molecular weight preferably 20,000 to 300,000, morepreferably 30,000 to 200,000, and even more preferably 40,000 to150,000. In this case, the weight average molecular weight is obtainedby carrying out measurement by gel permeation chromatography andconversion based on the calibration curve produced by using standardizedpolystyrenes.

A thermosetting adhesive can be obtained by adding a functionalgroup-containing amido-reactive compound to be reacted with the amido ofthe polyamide imide to the polyamide imide obtained in theabove-mentioned manner.

The amido-reactive compound is a compound having a functional group tobe reacted with the amido group of the polyamide imide by heating. Asthe amido-reactive compound, a polyfunctional epoxy compound and anoxetane compound can be exemplified, and the polyfunctional epoxycompound is preferably used.

Examples of the polyfunctional epoxy compound are bisphenol A type epoxyresin, tetrabromobisphenol A type epoxy resin, bisphenol F type epoxyresin, bisphenol S type epoxy resin, and biphenyl type epoxy resin,however the epoxy compound is not limited to these examples. One or moretypes of these exemplified compounds can be used.

The addition amount of the amido-reactive compound is preferably 10 to40 part by weight, more preferably 15 to 25 part by weight to polyamideimide 100 part by weight. If the addition amount of the amido-reactivecompound is less than 10 part by weight, the thermosetting property ofthe adhesive to be obtained tends to be deteriorated. If it exceeds 40part by weight, the cross-linked structure of the adhesive layer aftercuring the adhesive becomes dense and the brittle property of the resintends to be decreased.

The above-mentioned adhesive is preferable to further contain a curingpromoting agent. The curing promoting agent is a component to promotecuring of the mixture of the polyamide imide and the amido-reactivecompound and is preferably a compound promoting the curing ofparticularly the amido-reactive compound. Example of the curingpromoting agent are amines and imidazoles, however the agent is notlimited to them. One or more of these compounds can be used.

Examples of the amines are dicyandiamide, diaminodiphenylethane, andguanylurea, however the amines are not limited to these exemplifiedcompounds. Examples of the imidazoles are alkyl-substituted imidazolessuch as 2-ethyl-4-methylimidazole and benzoimidazole, however theimidazoles are not limited to these exemplified compounds.

The addition amount of the such a curing promoting agent may bedetermined depending on the type of the amido-reactive compound. Forexample, in the case a polyfunctional epoxy compound is used as theamido-reactive compound and amines are used as the curing promotingagent, amines are preferably added in an amount proper to adjust theepoxy equivalent of the polyfunctional epoxy compound and the equivalentof the active hydrogen of the amino groups of the amines to beapproximately same. In the case imidazoles are used as the curingpromoting agent, the imidazoles are preferably added in an amount of 0.1to 2.0 part by weight to the polyfunctional epoxy compound 100 part byweight. If the addition amount of the curing promoting agent isinsufficient, the uncured amido-reactive compound remains in theadhesive layer and the heat resistance of the adhesive layer tend to bedecreased. If it is excessive, the curing promoting agent remains in theadhesive layer and the insulating property of the adhesive layer tendsto be deteriorated after curing.

Based on the necessity, the adhesive may contain a rubber typeelastomer, a phosphorus type compound as a flame retardant, an inorganicfiller, a coupling agent, a pigment, a leveling agent, a defoamingagent, and an ion trapping agent.

Examples of the organic solvent to dissolve the adhesive in are ketonessuch as acetone, methyl ethyl ketone, and cyclohexanone; acetic acidesters such as ethyl acetate, butyl acetate, cellosolve acetate,propylene glycol monomethyl ether acetate, and carbitol acetate;cellosolves such as cellosolve and butyl cellosolve; carbitols such ascarbitol and butylcarbitol; aromatic hydrocarbons such as toluene andxylene; dimethylformamide, dimethylacetamide, and N-methylpyrrolidone,however the solvent is not limited to these exemplified solvents. One ormore kinds of these solvents may be used. It is required to select thesystem to sufficient dissolve the solid content.

The adhesive may be diluted in the above-mentioned organic solvents soas to adjust the solid content in a concentration of about 10%. A coresubstrate may be immersed in the obtained diluted solution and dried toform an adhesive layer (FIG. 2( g) and FIG. 3( g)).

Next, as shown in FIG. 1( h), FIG. 2( h), and FIG. 3( h), a one-sidemetal foil-bearing resin is laminated on the core substrate. The resinthickness (the insulating layers 9, 109, and 209) of the one-side metalfoil-bearing resin is about 10 to 100 μm, preferably 20 to 60 μm. Thesame resin compositions as those for the above-mentioned insulatinglayers 1, 101, and 201 can be used. The thickness of the metal foils 10,110, and 210 is preferably 0.3 to 3 μm and the metal foils similar tothose of the metal foils 2, 102, and 202 of the laminate plates can beused. The resin and the solvents in form of resin varnish may be appliedto the metal foils by using a kiss coater, a roll coater, or a commacoater. Or, a film-like resin may be laminated on the metal foils. Inthe case the resin varnish is applied to the metal foils, the resultinglaminates are heated and dried thereafter. The conditions are preferablyat 100 to 200° C. and 1 to 30 minutes. The amount of the remainingsolvent in the resin composition after the heating and drying ispreferably 0.2 to 10%. In the case the film-like resin is laminated onthe metal foil, the conditions are preferably at 50 to 150° C. and 0.1to 5 MPa vacuum or atmospheric pressure. Further, there is a laminatingand pressing method of the core substrate, prepreg, and copper foils. Inthis case also, based on the necessity, the adhesive layers 111 may beformed by applying the adhesive to the copper foils before theinsulating layer application. Usable adhesives, the thickness or thelike are same as those in the case of the above-mentioned adhesive layer103 (FIG. 2( h)).

Next, IVH 12, 112, and 212 are formed in the inter resin insulatinglayers from the metal foils as shown in FIG. 1( i), FIG. 2( i), and FIG.3( i). For the IVH formation method, laser is preferable to be used. Asthe laser to be employed in this case, gas laser of CO₂, CO, and excimerlaser, and solid laser such as YAG laser are available. As laser beamsource, known laser such as CO₂ laser, UV-YAG laser, and excimer lasercan be employed and CO₂ laser has a high processing speed and istherefore preferable and UV-YAG laser is suitable for forming via holeswith small diameters and is therefore preferable. Since high output canbe obtained easily, CO₂ laser is suitable for processing IVH with φ50 μmor larger. In the case of processing fine IVH with φ50 μm or smaller,YAG laser with shorter wavelength and excellent in the beamconcentration. As a laser hold formation method, a method using aconformal mask and direct laser processing method are available. Themethod using a conformal mask is a method involving forming openings atsites of metal foils where via holes are to be formed by etching andremoving the interlayer insulating resin layer by radiating laser beamwith a larger diameter than that of the opening by using the metal foilsas a mask. The direct laser processing method is a method for formingholes by radiating laser beam converged to have a via hole diameterdirectly to the metal foils. In the case of the direct laser processing,in order to increase the laser absorption ratio in the metal foilsurface, surface roughening treatment or blackening treatment may becarried out. In such a laser processing, if the peel strength betweenthe metal foils and the interlayer insulating layers is lower than 0.5kN/m, the metal foils in the periphery of the via hole are easily peeledand condition setting of the laser becomes difficult. If the peelstrength is 0.5 kN/m or higher, the metal peeling hardly occurs, and thepeel strength is preferably 0.8 kN/m or higher. Since smear is caused insuch via holes, it is preferable to remove the smear by usingpermanganic acid salt, chromic acid salt, or permanganic acid. Here, thepeel strength means the force required to peel the metal foils at 50mm/min in the vertical direction and expressed on the basis of load perunit width (kN/m).

Next, the resin residue in the inside of the IVH is removed by usingpermanganic acid salt, chromic acid salt, or permanganic acid.

Next, a catalyst core is supplied to the metal foils and the IVHinsides. To supply the catalyst core, a noble metal ion or palladiumcolloid is used.

Next, as shown in FIG. 1( j), FIG. 2( j), and FIG. 3( j), thinelectroless plating layers 13, 113, and 213 are formed on the metalfoils and IVH insides to which the catalyst core is supplied. For theelectroless plating, commercialized electroless copper plating solutionssuch as CUST 2000 (trade name, manufactured by Hitachi Chemical Co.,Ltd.) and CUST 201 (trade name, manufactured by Hitachi Chemical Co.,Ltd.) can be employed, however the plating is not limited to theexamples. These electroless copper plating solutions contain mainlycopper sulfate, formalin, a complexing agent, and sodium hydroxide. Thethickness of the plating is sufficient if the next electroplating can becarried out thereon and it is about 0.1 to 1 μm.

Next, as shown in FIG. 1( k), FIG. 2( k), and FIG. 3( k), plating resist14, 114, and 214 is formed on the electroless plating layers. Thethickness of the plating resist is preferably as same as or thicker thanthe thickness of a conductor for planting thereafter. Examples of theresin to be used for the plating resist are liquid phase resist such asPMER P-LA900PM (trade name; manufactured by Tokyo Ohka Kogyo Co., Ltd.)and dry films such as HW-425 (trade name, manufactured by HitachiChemical Co., Ltd.) and RY-3025 (trade name, manufactured by HitachiChemical Co., Ltd.). The plating resist should not be formed on theportions to be via holes and a conductor circuit.

Next, as shown in FIG. 1( l), FIG. 2( l), and FIG. 3( l), circuitpatterns 15, 115, and 215 are formed by electroplating. A copper sulfateelectroplating to be used commonly for a printed wiring board may beused. The thickness of the plating is sufficient if it is used as acircuit conductor and preferably in a range of 1 to 100 μm, morepreferably in a range of 5 to 50 μm.

Next, the resist is separated by an alkaline separation solution,sulfuric acid, or a commercialized resist separation solution.

Next, copper in the portions other than the pattern parts is removed byan etching solution containing sulfuric acid in a concentration of 10 to300 g/L and hydrogen peroxide in a concentration of 10 to 200 g/L asmain components to complete circuit formation (FIG. 1( m), FIG. 2( m),and FIG. 3( m))

Further, as shown in FIG. 2( n), FIG. 2( n), and FIG. 3( n), goldplating 16, 116, and 216 may be carried out on the circuit. As a goldplating method, steps may be carried out as follows: the conductorinterface is activated by an activation solution such as SA-100 (tradename; manufactured by Hitachi Chemical Co., Ltd.); an electroless nickelplating in a thickness of 1 to 10 μm is carried out by using NIPS-100(trade name; manufactured by Hitachi Chemical Co., Ltd.); a displacementgold plating in a thickness of 0.01 to 0.1 μm is carried out by usingHGS-100 (trade name; manufactured by Hitachi Chemical Co., Ltd.); andthen an electroless gold plating in a thickness of about 0.1 to 1 μm iscarried out. Since the resin layer is flat in the invention, theelectroless nickel deposition and displacement plating gold depositionon the resin can be suppressed. Further, if electroless palladiumplating is carried out between the electroless nickel plating andelectroless gold plating as described in Japanese Patent ApplicationLaid-Open No. 11-140659, the connection reliability is further improved.The electroless palladium plating may be carried out to be about 0.01 to1 μm thick by using Pallet (trade name; KOJIMA Chemical Co., Ltd.). Inconsideration of the electric properties, the electroless nickel platingmay be eliminated. These combinations may differ depending on the usesof the product and determined based on the cost, electric properties,and connection reliability.

The invention is effective in cases of employing any of theabove-mentioned techniques. The disclosure of Japanese PatentApplication Laid-Open No. 11-140659 is expressly incorporated herein byreference its entirety.

In terms of the practical usability of the printed wiring board andsuppression of the defects in the process, the peel strength of theconductor circuit with a width of 1 mm from the insulating resin layeris preferably 0.6 kN/m or higher and the peel strength of the conductorcircuit with a width of 1 mm from the insulating resin layer is furtherpreferably 0.4 kN/m or higher after heating at 150° C. for 240 hours.

EXAMPLES

Hereinafter, the embodiments of the invention will be described alongwith FIGS. 1( a) to 1(f).

Example 1A

The following metal foil A was produced.

Metal Foil A

Chromium plating was continuously carried out on the bright face of anelectrolytic copper foil (a carrier copper foil) with a width of 510 mmand a thickness of 35 μm in the following conditions to form a chromiumplating layer (a separation layer) with a thickness of 1.0 mg/dm². Thesurface roughness (ten-point mean surface roughness) Rz after thechromium plating formation was 0.5 μm. The surface roughness wasmeasured according to JIS-B-0601.

Solution composition: chromium trioxide 250 g/L and sulfuric acid 2.5g/L,

Bath temperature: 25° C.,

Anode: lead, and

Electric current density: 20 A/dm².

Next, electric copper plating in a thickness of 2.0 μm was carried outin the following bright conditions. The metal foil surface roughness Rzafter the electric copper plating was 0.6 μm.

Solution composition: copper sulfate pentahydrate 100 g/L, sulfuric acid150 g/L, and chloride ion 30 ppm,

Bath temperature: 25° C.,

Anode: lead, and

Electric current density: 10 A/dm².

Next, zinc anti-rust treatment was carried out by electric plating inthe following bright conditions.

Solution composition: zinc 20 g/L and sulfuric acid 70 g/L,

Bath temperature: 40° C.,

Anode: lead,

Electric current density: 15 A/dm².

Electrolytic time: 10 seconds.

Next, successively the following chromate treatment was carried out.

Solution composition: chromic acid 5.0 g/L, pH: 11.5,

Bath temperature: 55° C.,

Anode: lead, and

Immersion period: 5 seconds.

Next, the following silane coupling treatment was carried out.

Solution composition: 3-aminopropyltrimethoxysilane 5.0 g/L,

Bath temperature: 25° C., and

Immersion period: 10 seconds.

After silane coupling treatment, the metal foil was dried at 120° C. toadsorb the coupling agent to the metal foil surface to obtain a metalfoil A. The metal foil surface roughness Rz was 0.6 μm at that time.

The following resin composition B was produced. The resin composition Bwas used for an insulating layer later.

Resin Composition B

Polyphenylene ether resin (trade name: PKN 4752, manufactured by GEPlastics Japan Ltd.) 20% by weight, 2,2-bis(4-cyanatophenyl)propane(trade name: Arocy B-10, manufactured by Asahi Ciba Co., Ltd.) 40% byweight, a phosphorus-containing phenol compound (trade name: HCA-HQ,Sanko Co., Ltd.) 8% by weight, manganese naphthenate (Mn content=6% byweight, manufactured by Nihon Kagaku Sangyo Co., Ltd.) 0.1% by weight,2,2-bis(4-glycidylphenyl)propane (trade name: DER 331L, manufactured byDow Chemical Japan Ltd.) 32% by weight were dissolved in toluene at 80°C. to obtain polyphenylene ether cyanate type resin composition varnish,which was the resin composition B.

Next, a glass cloth with a thickness of 0.2 mm was immersed in the resincomposition B and dried at 120° C. for 5 minutes to obtain a prepreg.Four sheets of the prepreg were laminated and the metal foils A werelaminated on the top and bottom of the obtained laminate and theresulting laminate was press-formed at 170° C. and 2.45 MPa for 1 hourand the carrier foils on the copper foils were peeled to obtain acopper-clad laminated board comprising the insulating layer (the prepreglayer) 1 and the metal foils 2 as shown in FIG. 1( a).

As shown in FIG. 1( b), a penetrating through hole 4 with a diameter 80μm was formed by a carbon dioxide gas impact laser hole formingapparatus L-500 (trade name, manufactured by Sumitomo Heavy Industries,Ltd.) through the metal foil the insulating layer, and smear was removedby immersing the board in an aqueous solution mixture of potassiumpermanganate 65 g/L and sodium hydroxide 40 g/L at a solutiontemperature of 70° C. for 20 minutes.

After that, HS-201B (trade names; manufactured by Hitachi Chemical Co.,Ltd.), which is a palladium catalyst, was supplied and then usingCUST-201 (trade names; manufactured by Hitachi Chemical Co., Ltd.),electroless copper plating was carried out at a solution temperature of25° C. for 30 minutes to form 0.5 μm-thick electroless copper platinglayers 5 as shown in FIG. 1( c). The palladium catalyst supplyconditions are shown in Table 1.

TABLE 1 Treatment Treatment Step Treatment Solution Condition CleanerCLCc-501 60° C., 5 min Warm Water Washing Pure Water 40° C., 4 minEtching Ammonium 25° C., 10 sec. Peroxodisulfate 187 g/1 Flowing WaterWashing Pure Water 25° C., 3 min. Acid Treatment 10 Vol. % Sulfuric Acid25° C., 3 min. Flowing Water Washing Pure Water 25° C., 2 min. CatalystSupply Pretreatment PD301 25° C., 2 min. Catalyst Supply TreatmentHS201-B 25° C., 8 min. Flowing Water Washing Pure Water 25° C., 3 min.Adhesion Promoting Agent ADP-201 25° C., 4 min. Flowing Water WashingPure Water 25° C., 2 min.

As shown in FIG. 1( d), RY-3325 (trade names; manufactured by HitachiChemical Co., Ltd.), which is a dry film photoresist, was laminated onthe surface of the electroless plating layers 5 and through a photomaskmasking the parts on which electric copper plating was to be carriedout, UV exposure was carried out and the exposed parts were developed toform plating resist 6.

As shown in FIG. 1( e), electric copper plating in a thickness of about20 μm was carried out by using a copper sulfate bath in conditions of asolution temperature of 25° C. and a current density of 1.0 A/dm² toform a circuit pattern 7 with the minimum circuit conductorwidth/circuit conductor interval (L/S)=23/17 μm.

Next, as shown in FIG. 1( f), after the dry film was removed by HTO(trade name; manufactured by Nichigo-Morton Co., Ltd.), which is aresist separation solution, Cu in portions other than the pattern partswas removed by etching using an etching solution with a composition ofH₂SO₄ 100 g/L and H₂O₂ 10 g/L to produce an inner layer substrate.

Next, electroless gold plating 20 (not illustrated) was carried out inthe outermost layer to complete the substrate. The electroless goldplating conditions are shown in Table 2.

TABLE 2 Solution Immersion Step Solution Concentration Temperature TimeDegreasing Z-200 60° C. 1 min. Water Washing 25° C. 2 min. Soft EtchingAmmonium 100 g/L 25° C. 1 min. Peroxodisulfate Water Washing 25° C. 2min. Acid Washing Sulfuric Acid 10 vol % 25° C. 1 min. Water Washing 25°C. 2 min. Activation Treatment SA-100 25° C. 5 min. Water Washing 25° C.2 min. Electroless Nickel Phosphorus NIPS-100 85° C. 20 min.  PlatingWater Washing 25° C. 2 min. Electroless Nickel Boron Plating Top Chemi65° C. 5 min. Alloy 66 Water Washing 25° C. 2 min. Electroless NickelPalladium Pallet 70° C. 5 min. Plating Water Washing 25° C. 2 min.Displacement Gold Plating HGS-100 85° C. 10 min.  Water Washing 25° C. 2min. Electroless Gold Plating HGS-2000 65° C. 40 min.  Remarks) Z-200(trade name: manufactured by World Metal Co., Ltd.) SA-100 (trade names;manufactured by Hitachi Chemical Co., Ltd.) NIPS-100 (trade names;manufactured by Hitachi Chemical Co., Ltd.) Top Chemi Alloy 66 (tradenames; manufactured by Okuno Chemical Industries Co., Ltd.) Pallet(trade name; KOJIMA Chemicals Co., Ltd.) HGS-100 (trade names;manufactured by Hitachi Chemical Co., Ltd.) HGS-2000 (trade names;manufactured by Hitachi Chemical Co., Ltd.)

Comparative Example 1A

A substrate was produced in the same manner as Example 1, except thatMicrosyn (trade name: Mitsui Mining and Smelting Co., Ltd.) with 3.0 μmwas used n place of the metal foil A. The surface roughness Rz ofMicrosyn was 3.5 μm. After the etching, the minimum circuit conductorwidth/circuit conductor interval=15/25 μm.

Measurement Condition

(1) Wiring Finishing

The minimum circuit conductor width/circuit conductor interval (L/S) wasconfirmed by processing the images taken by an optical microscope.OLYMPUS MX50 (trade name: manufactured by Olympus Corporation) was usedas the optical microscope. MCP-550 (trade name: manufactured by MoritexCorporation) was used for the image processing. The measurement wascarried out at aimed finishing L/S=50/50, 40/40, 30/30, 25/25, and 20/20μm. The results are shown in Table 3.

(2) Evaluation of Gold Plating Deposition Amount on Resin Composition

Nickel/gold plating deposition is not necessarily caused only on thecircuit but often caused as to form a train from the circuit as shown inFIG. 4. Therefore, the value calculated by dividing the difference ofthe top (St) and the bottom (Sb) of the circuit with 2, that is(St−Sb)/2, was quantified as the gold plating deposition amount on theresin. The gold plating deposition amount was confirmed by processingimages taken by the optical microscope. The results are the averages ofvalues measured at 20 points respectively. The measurement was carriedout at aimed finishing L/S=50/50, 40/40, 30/30, 25/25, and 20/20 μm.

Results

TABLE 3 Measurement Pitch Aimed 10 μm 80 μm 60 μm 50 μm 40 μm PointsFinishing 50/50 μm 40/40 μm 30/30 μm 25/25 μm 20/20 μm Example 1Finishing 50/50 μm 40/40 μm 30/30 μm 25/25 μm 20/20 μm Gold Plating 0 μm0 μm 0 μm 0 μm 0 μm Deposition Amount Comparative Finishing 45/55 μm35/45 μm 25/35 μm 20/30 μm 15/25 μm Example 1 Gold Plating 1 μm 3 μm 5μm 7 μm 7 μm Deposition Amount

With respect to the substrate produced in Example 1A, the copper foilhardly remained on the resin layer at the time of etching and therefore,circuit formability was good and wiring was finished with aimedfinishing value and further, no gold deposition on the resin was caused.On the other hand, with respect to the substrate produced in Example 1A,it was required to etch the residue of the copper foil on the resinlayer at the time of etching, and therefore, wiring top width (L) wasmade thin. It was found that as the wiring became thinner, the goldplating deposition amount was increased more. It is supposedlyattributed to that the wiring becomes thinner, the solution flow orcirculation is deteriorated and etching residues are caused.

Hereinafter, another embodiment of the invention will be described alongwith FIG. 2.

Example 1B

The following resin composition A was produced.

Resin Composition A

A separable flask 500 mL capacity equipped with a Deen/Stark refluxingcooling apparatus, a thermometer, and a stirrer was loaded with(4,4′-diamino)dicyclohexylmethane as an alicyclic diamine compound(trade name: Wondamine HM (abbreviated as WHM), manufactured by NewJapan Chemical Co., Ltd.) 45 mmol, a reactive silicone oil X-22-161-B assiloxanediamine (trade name: manufactured by Shin-Etsu Chemical Co.,Ltd., amine equivalent 1,500) 5 mmol, trimellitic anhydride (TMA) 105mmol, and N-methyl-2-pyrrolidone as a non-proton polar solvent 145 g andthe mixture was stirred at 80° C. for 30 minutes.

On completion of stirring, toluene 100 mL as an aromatic hydrocarbonazeotropic with water was added and the resulting reaction solution washeated to 160° C. and refluxed for 2 hours. When it was confirmed that atheoretical quantity of water was pooled in a water quantitativereception apparatus and no water flow was observed, water and toluene inthe water quantitative reception apparatus were removed and toluene inthe reaction solution was removed by heating to 190° C.

After the solution in the flask was cooled to a room temperature,4,4′-diphenylmethane diisocyanate (MDI) as diisocyanate 60 mmol wasadded and the temperature was increased to 190° C. and reaction wascarried out for 2 hours to obtain an NMP solution of polyamide imideresin. Next, YDCN-500-10 (manufactured by Tohto Kasei Co., Ltd.) as anepoxy resin was added in a proper amount so as to adjust the total solidcontent concentration to be 10%, and further 2-ethyl-4-methylimidazoleas a curing promoting agent was added in a proper amount of 1% by weighton the basis of the solid content of the epoxy resin and the resultingsolution was diluted with dimethylacetamide to obtain thermosettingresin varnish (solid content 10%), which was used as the resincomposition A.

Next, a metal foil B was produced as follows by using the resincomposition A.

Metal Foil B

The resin composition A was applied to the silane coupling agent-treatedface of the metal foil A obtained in Example 1A. After the application,the composition A was dried at 160° C. for about 1 minute to decreasethe remaining solvent to 1% or less and obtain the metal foil B. Thethickness of the applied resin composition A was 2.0 μm.

A glass cloth with a thickness of 0.2 mm (basic weight, Hyoryo: 210g/m²) was immersed in the resin composition B obtained in Example 1A anddried at 12° C. for 5 minutes to obtain prepreg. Four sheets of theprepreg were laminated and the metal foils B were laminated on the topand bottom of the obtained laminate in such a manner that the facescoated with the resin composition A were in the prepreg sides and theresulting laminate was press-formed at 170° C. and 2.45 MPa for 1 hourand the carrier foils on the copper foils were peeled to obtain acopper-clad laminated board comprising the insulating layer 101, theadhesive layers 103, and the metal foils 102 as shown in FIG. 2( a).

Next, an inner layer substrate (a core substrate) was produced similarlyto Example 1A (FIG. 2( f)).

Next, the entire body of the substrate was immersed in the solution ofthe resin composition A, pulled out, and dried at 160° C. for 10 minutesto coat the entire body of the substrate with the resin composition A asshown in FIG. 2( b) to form adhesive layers 108. The coating thicknesswas about 2 μm after drying.

Next, the resin composition B was applied to the metal foils B and driedat 160° C. for 5 minutes. The coating thickness was about 2 μm afterdrying. The resin composition B side of the copper foils B after theresin coating and the adhesive layers 108 were press-formed at 170° C.and 2.45 MPa for 1 hour and then the carrier foils on the copper foilswere peeled to produce the substrate shown in FIG. 2( h). Accordingly,the insulating layers 109, the adhesive layers 111, and the metal foils110 were formed.

As shown in FIG. 1( i), an IVH 112 with a diameter 50 μm was formed by acarbon dioxide gas impact laser hole forming apparatus L-500 (tradename, manufactured by Sumitomo Heavy Industries, Ltd.) from the metalfoil and smear was removed by immersing the board in an aqueous solutionmixture of potassium permanganate 65 g/L and sodium hydroxide 40 g/L ata solution temperature of 70° C. for 20 minutes.

After that, HS-201B (trade names; manufactured by Hitachi Chemical Co.,Ltd.), which is a palladium catalyst, was supplied and then usingCUST-201 (trade names; manufactured by Hitachi Chemical Co., Ltd.),electroless copper plating was carried out at a solution temperature of25° C. for 30 minutes to form 0.5 μm-thick electroless copper platinglayers 113 as shown in FIG. 1( c). The palladium catalyst supplyconditions were as shown in Table 1.

As shown in FIG. 2( k), RY-3325 (trade names; manufactured by HitachiChemical Co., Ltd.), which is a dry film photoresist, was laminated onthe surface of the electroless plating layers 5 and through a photomaskmasking the parts on which electric copper plating was to be carriedout, UV exposure was carried out and the exposed parts were developed toform plating resist 114.

As shown in FIG. 2( i), electric copper plating in a thickness of about20 μm was carried out by using a copper sulfate bath in conditions of asolution temperature of 25° C. and a current density of 1.0 A/dm² toform a circuit pattern 115 with the minimum circuit conductorwidth/circuit conductor interval (L/S)=23/17 μm.

Next, as shown in FIG. 2( m), after the dry film was removed by HTO(trade name; manufactured by Nichigo-Morton Co., Ltd.), which is aresist separation solution, Cu in portions other than the pattern partswas removed by etching using an etching solution with a composition ofH₂SO₄ 100 g/L and H₂O₂ 10 g/L to produce an inner layer substrate.

The minimum circuit conductor width/circuit conductor interval (L/S)after the etching was 20/20 μm.

Next, as shown in FIG. 2( n), electroless gold plating 116 was carriedout in the outermost layer. The electroless gold plating conditions wereas shown in Table 2.

Example 2B

A substrate was produced in the same manner as Example 1B, except thatGEA-679-FG, which is prepreg with 60 μm thickness and metal foils B werelaminated on the inner substrate in place of application and heating ofthe resin composition B after the coating in the step G.

Example 3B

A substrate was produced in the same manner as Example 1B, except thatGEA-679-F, which is prepreg with 60 μm thickness and metal foils B werelaminated on the inner substrate in place of application and heating ofthe resin composition B after the coating in the step G.

Example 4B

A substrate was produced in the same manner as Example 1B, except thatthe resin composition A was applied in a proper amount so as to adjustthe thickness to be 5 μm at the time of forming the adhesive layers byapplying the resin composition A to the silane coupling agent-treatedfaces of the metal foils A, that is at the time of producing the metalfoil B.

Example 5B

A substrate was produced in the same manner as Example 1B, except thatthe resin composition A was applied in a proper amount so as to adjustthe thickness to be 6 μm at the time of forming the adhesive layers byapplying the resin composition A to the silane coupling agent-treatedfaces of the metal foils A, that is at the time of producing the metalfoil B.

Comparative Example 1B

A substrate was produced in the same manner as Example 1B, except thatthe resin composition A was not applied in the step G.

Comparative Example 2B

A substrate was produced in the same manner as Example 1B, except thatGEA-679-FG, which is prepreg with 60 μm thickness and metal foils A werelaminated on the inner layer substrate coated with the resin compositionA in place of press-formation of the metal foils B coated with the resincomposition B after the coating in the step G.

Production of Sample for Evaluation of Properties

Test specimens for measuring the physical properties, dielectricconstant, and dielectric dissipation factor of the insulating layer inthe outermost layer were produced. Samples for evaluating the propertiesof the insulating layer in the outermost layer were produced.

Sample for Evaluation of Properties for Example 1B

The resin composition A was applied in a thickness of 2 μm to a bothsides-untreated 18 μm-thick copper foil (Rz=0.6 μm) and the resincomposition B was applied in a thickness of 40 μm on the metal foil Band both foil were laminated in such a manner that the resin faces arestuck to each other and the resulting laminate was press-formed at 170°C. and 2.45 MPa for 1 hour and the entire face of the copper foil wasetched to produce a sample for property evaluation.

Sample for Evaluation of Properties for Example 2B

The resin composition A was applied in a thickness of 2 μm to a bothsides-untreated 18 μm-thick copper foil (Rz=0.6 μm) and GEA-679-FG,which is prepreg with a thickness of 60 μm and the metal foil B weresuccessively laminated thereon and the resulting laminate waspress-formed at 170° C. and 2.45 MPa for 1 hour and the entire face ofthe copper foil was etched to produce a sample for property evaluation.

Sample for Evaluation of Properties for Example 3B

A sample was produced in the same manner as the sample for propertyevaluation for Example 2B, except that GEA-679-F was used in place ofGEA-679-FG.

Sample for Evaluation of Properties for Example 4B

A sample was produced in the same manner as the sample for propertyevaluation for Example 1B, except that coating was carried out in athickness of 5 μm using the resin composition A at the time of producingthe metal foil B.

Sample for Evaluation of Properties for Example 5B

A sample was produced in the same manner as the sample for propertyevaluation for Example 1B, except that coating was carried out in athickness of 6 μm using the resin composition A at the time of producingthe metal foil B.

Sample for Evaluation of Properties for Comparative Example 1B

A sample was produced in the same manner as the sample for propertyevaluation for Example 1B, except that both sides-untreated 18 μm-thickcopper foil (Rz=0.6 μm) was not coated with the resin composition A.

Sample for Evaluation of Properties for Comparative Example 2B

A sample was produced in the same manner as the sample for propertyevaluation for Example 2B, except that the metal foil A was used inplace of the metal foil B.

Test Method

Measurement of Thermal Expansion Coefficient

The thermal expansion coefficient of the samples for evaluation ofproperties was measured by a TMA (thermomechanical analyzer) test forthe samples for evaluation of properties respectively cut into strips(20 mm×5 mm). The measurement was carried out at 20° C. in biaxialdirection (X-direction and Y direction). The measurement was carried outtwice for each sample and the value at the second time was employed asdata. The TMA (thermomechanical analyzer) test is shown in Table 4.

TABLE 4 TMA (Thermomechanical Analyzer) Test Condition Item ConditionApparatus TMA 2940, manufactured by Du Pont Ltd. Measurement Temperature0° C.~150° C., 10° C./min. Mode, Load Tensile 5 gMeasurement of Tensile Strength

The tensile strength of the samples for evaluation of properties wasmeasured by a tensile strength test for the samples for evaluation ofproperties respectively cut into a strip-like shape. The measurement wascarried out at 20° C. in biaxial direction (X-direction and Y direction)and the average was calculated. The tensile strength test conditions areshown in Table 5.

TABLE 5 Tensile Strength Test Condition Item Condition Apparatus 5-tTensilon RTC-1350A, manufactured by Orientech Co., Ltd. Speed/Span 0.5mm/min./100 mm Specimen Size 220 mm × 10 mmMeasurement of Dielectric Constant and Dielectric Dissipation Factor

The dielectric constant and dielectric dissipation factor of each samplefor evaluation of properties were measured. The measurement was carriedout at 20° C. The measurement conditions are shown in Table 6.

TABLE 6 Condition of Dielectric Constant and Dielectric DissipationFactor Test Item Condition Apparatus Impedance/Material analyzer HP4291,manufactured by Hewlett-Packard Development Company, L.P. MeasurementFrequency 1 GH_(z) Specimen Size 25 mn × 25 mnMeasurement of Conductor Circuit Peel Strength

The outer layer conductor circuit peel strength of the substratesproduced in Examples 1B to 5B and Comparative Examples 1B and 2B wasmeasured. The vertical peel strength was measured as the peel strength.The peel strength was measured as initial values and values afterheating at 150° C. for 240 hours. The measurement was carried outconstantly at 20° C. The measurement conditions are shown in Table 7.

TABLE 7 Test Conditions for Conductor Circuit Peel Strength ItemCondition Apparatus Autograph AC-100 C, manufactured by ShimadzuCorporation Peeling Speed 50 mm/min. Test Width 1 mmConnection Reliability Evaluation

The connection reliability evaluation of the substrates produced inExamples 1B to 5B and Comparative Examples 1B and 2B was carried out.The patterns shown in FIG. 5 were used for the evaluation. In Table 5, aconductor circuit 301, an IVH 302, and an insulating layer 303 areshown. The designs of the patterns shown in FIG. 5 are shown in Table 8.The connection reliability was evaluated by repeating cooling andheating cycle of −60° C. for 30 min and at 125° C. for 30 min 1,000times and if the resistance value alteration was in +10% of the initialvalue, the connection reliability was determined to be qualified.

TABLE 8 Design of Connection Reliability Evaluation Pattern UnitEmployed IVH Diameter μm 80 IVH Pitch mm 1.27 Inner Layer Pad Diameterμm 150 Outer Layer Land Diameter μm 150 IVH Number holes 400Moisture Absorption Heat Resistant Test

The substrates obtained in Examples 1B to 5B and Comparative Examples 1Band 2B were subjected to the moisture absorption heat resistant test.The test was carried out by treating the respective substrates inconditions of 121° C., 100% humidity, 2 atmospheric pressure, and 96hours and confirming whether blister occurred or not. A saturated typePCT apparatus PC-242 manufactured by Hirayama Manufacturing Corp. wasemployed.

Test Results

The evaluation results of the substrates obtained in Examples 1B to 5Band Comparative Examples 1B and 2B are shown in Table 9. The substratesobtained in Examples 1B to 5B were found having high copper foil peelstrength and good reliability in the moisture absorption heat resistanttest. On the other hand, the substrate of Comparative Examples 1B wasfound causing troubles such as blister between the inner circuit and theinsulating layer in the reliability test since no adhesive layer coatingwas carried out on the inner circuit in the substrate. Also, thesubstrate of Comparative Examples 2B was found having high peel strengthof the copper foil and insufficient reliability.

TABLE 9 Copper Foil Peel Strength Reliability Test Test Thermalexpansion Tensile Dielectric Dielectric Before After Connection MoistureItem CTE X CTE Y Strength Constant Dissipation Heating HeatinReliability Absorption Unit (ppm/° C.) (ppm/° C.) MP_(a) — — KN/m KN/m —— Example 1 50 50 60 2.8 0.005 1.5 1.3 Good No particular Example 2 1315 290 4.8 0.014 1.5 1.4 Good No particular Example 3 11 12 290 4.70.014 1.5 1.4 Good No particular Example 4 47 47 62 3.0 0.007 1.5 1.4Good No particular Example 5 47 47 62 3.1 0.008 1.5 1.4 Poor Noparticular Comparative 51 51 60 2.7 0.004 1.5 1.4 Poor Blister Example 1Comparative 13 15 290 4.8 0.014 0.4 0 Poor Blister Example 2

Further, in various properties, the substrate of Example 1B had a lowdielectric constant and dielectric dissipation factor of the insulatinglayer and was therefore expected to have good electric properties. Thesubstrates of Example 2B and 3B had a low dielectric constant and a hightensile strength and were therefore expected to have good dispositionreliability.

Further, an embodiment of the invention will be described along withFIG. 2.

Example 1C

The metal foil B was produced in the same manner as Example 1B, exceptthat the thickness after drying was changed to be 1.0 μm from 2.0 μm.After that, a core substrate was produced in the same manner as Example1B (FIG. 2( f)). The surface roughness Rz of the insulating layer of thecore substrate was 0.5 μm and the surface roughness Rz of the conductorcircuit was 1.2 μm. The surface roughness was measured according toJIS-B-0601.

Next, the entire body of the substrate was immersed in the solution ofthe resin composition A, pulled out, and dried at 160° C. for 10 minutesto decrease the remaining solvent to 1% or lower and coat the entirebody of the substrate with the resin composition A as shown in FIG. 2(g). The coating thickness was about 2 μm after drying.

GEA-679-FG, which is 60 μm-thick prepreg, (trade names; manufactured byHitachi Chemical Co., Ltd.) and metal foils B composed of an adhesivelayer 111 and the metal layer 110 were laminated on the core substrateafter the coating and the resulting laminate was press-formed at 170° C.and 2.45 MPa for 1 hour and then the carrier foils on the copper foilswere peeled to obtain a substrate as shown in FIG. 2( h).

After that a printed wiring board was produced in the same manner asthat of Example 1B (FIG. 2( n)).

Example 2C

A substrate was produced in the same manner as Example 1C, except thatthe resin composition A was produced in the following production method.

Resin Composition A-2

A separable flask 500 mL capacity equipped with a Deen/Stark refluxingcooling apparatus, a thermometer, and a stirrer was loaded with(4,4′-diamino)dicyclohexylmethane as an alicyclic diamine compound(trade name: Wondamine HM (abbreviated as WHM), manufactured by NewJapan Chemical Co., Ltd.) 140 mmol, Jeffamine D-2000 (trade name:manufactured by Sun Techno Chemical Co., Ltd.) as an aliphatic diamine35 mmol, trimellitic anhydride (TMA) 368 mmol, andN-methyl-2-pyrrolidone (NMP) as a non-proton polar solvent 413 g and themixture was stirred at 80° C. for 30 minutes.

On completion of stirring, toluene 120 mL as an aromatic hydrocarbonazeotropic with water was added and the resulting reaction solution washeated to 160° C. and refluxed for 2 hours. When it was confirmed that atheoretical quantity of water was pooled in a water quantitativereception apparatus and no water flow was observed, water and toluene inthe water quantitative reception apparatus were removed and toluene inthe reaction solution was removed by heating to 190° C.

After the solution in the flask was cooled to a room temperature,4,4′-diphenylmethane diisocyanate (MDI) as diisocyanate 210 mmol wasadded and the temperature was heated to 190° C. and reaction was carriedout for 2 hours to obtain an NMP solution of polyamide imide resin.Next, YDCN-500-10 (manufactured by Tohto Kasei Co., Ltd.) as an epoxyresin was added in a proper amount so as to adjust the total solidcontent concentration to be 10%, and further 2-ethyl-4-methylimidazoleas a curing promoting agent was added in a proper amount of 1% by weighton the basis of the solid content of the epoxy resin and the resultingsolution was diluted with dimethylacetamide to obtain thermosettingresin varnish (solid content 10%).

Example 3C

A substrate was produced in the same manner as Example 1C, except thatthe resin composition A was produced in the following production method.

Resin Composition A-3

A separable flask 500 mL capacity equipped with a Deen/Stark refluxingcooling apparatus, a thermometer, and a stirrer was loaded withJeffamine D-2000 (trade name: manufactured by Sun Techno Chemical Co.,Ltd.) as an aliphatic diamine 30 mmol, reactive Silicone Oil X-22-161-B(trade name: manufactured by Shin-Etsu Chemical Co., Ltd., amineequivalent 1,500) as siloxanediamine 10 mmol,(4,4′-diamino)diphenylmethane (abbreviated as DDM) as an aromaticdiamine 60 mmol, trimellitic anhydride (TMA) 210 mmol, andN-methyl-2-pyrrolidone (NMP) as a non-proton polar solvent 407 g and themixture was stirred at 80° C. for 30 minutes.

On completion of stirring, toluene 100 mL as an aromatic hydrocarbonazeotropic with water was added and the resulting reaction solution washeated to 160° C. and refluxed for 2 hours. When it was confirmed that atheoretical quantity of water was pooled in a water quantitativereception apparatus and no water flow was observed, water and toluene inthe water quantitative reception apparatus were removed and toluene inthe reaction solution was removed by heating to 190° C.

After the solution in the flask was cooled to a room temperature,4,4′-diphenylmethane diisocyanate (MDI) as diisocyanate 210 mmol wasadded and the temperature was heated to 190° C. and reaction was carriedout for 2 hours to obtain an NMP solution of polyamide imide resin.Next, YDCN-500-10 (manufactured by Tohto Kasei Co., Ltd.) as an epoxyresin was added in a proper amount so as to adjust the total solidcontent concentration to be 10%, and further 2-ethyl-4-methylimidazoleas a curing promoting agent was added in a proper amount of 1% by weighton the basis of the solid content of the epoxy resin and the resultingsolution was diluted with dimethylacetamide to obtain thermosettingresin varnish (solid content 10%).

Example 4C

A substrate was produced in the same manner as Example 1C, except thatthe resin composition A was produced in the following production method.

Resin Composition A-4

A separable flask 500 mL capacity equipped with a Deen/Stark refluxingcooling apparatus, a thermometer, and a stirrer was loaded withJeffamine D-2000 (trade name: manufactured by Sun Techno Chemical Co.,Ltd.) as an aliphatic diamine 30 mmol, (4,4′-diamino)diphenylmethane(abbreviated as DDM) as an aromatic diamine 120 mmol, trimelliticanhydride (TMA) 315 mmol, and N-methyl-2-pyrrolidone (NMP) as anon-proton polar solvent 442 g and the mixture was stirred at 80° C. for30 minutes.

On completion of stirring, toluene 100 mL as an aromatic hydrocarbonazeotropic with water was added and the resulting reaction solution washeated to 160° C. and refluxed for 2 hours. When it was confirmed that atheoretical quantity of water was pooled in a water quantitativereception apparatus and no water flow was observed, water and toluene inthe water quantitative reception apparatus were removed and toluene inthe reaction solution was removed by heating to 190° C.

After the solution in the flask was cooled to a room temperature,4,4′-diphenylmethane diisocyanate (MDI) as diisocyanate 180 mmol wasadded and the temperature was heated to 190° C. and reaction was carriedout for 2 hours to obtain an NMP solution of polyamide imide resin.Next, YDCN-500-10 (manufactured by Tohto Kasei Co., Ltd.) as an epoxyresin was added in a proper amount so as to adjust the total solidcontent to be 10%, and further 2-ethyl-4-methylimidazole as a curingpromoting agent was added in a proper amount of 1% by weight on thebasis of the solid content of the epoxy resin and the resulting solutionwas diluted with dimethylacetamide to obtain thermosetting resin varnish(solid content 10%).

Comparative Example 1C

A substrate was produced in the same manner as Example 1C, except thatthe step of immersing the entire body of the core substrate was notimmersed in the resin composition A.

Measurement of Sample for Adhesive Strength Evaluation

The adhesion force of a conductive circuit on a core substrate and aninsulating layer layered on the conductor circuit were measured by amodel experiment. The method will be described as follows.

Production of Evaluation Sample of Example 1C

MEC etch BOND CZ-8100 (trade name: manufactured by Mech Co., Ltd.) wassprayed at the solution temperature 35° C. and spraying pressure 0.15MPa to both sides of MCL-E-679, which is a copper-clad laminated board,with a thickness of 0.6 μm to carry out surface-roughening of coppersurface and form about 3 μm roughness and next, the resulting board wasimmersed in MEC etch BOND CZ-8300 (trade name: manufactured by Mech Co.,Ltd.) at the solution temperature 25° C. for 20 seconds to carry outanti-rust treatment for the copper surface.

On the other hand, the bright surface (Rz=0.6 μm) of a 18 μm-thickcopper foil was coated with the resin composition A. After the coating,the foil was dried at 160° C. for 1 minute so as to suppress theremaining solvent 1% or lower. The thickness of the applied resincomposition was 2.0 μm.

Next the resin-coated face of the 18 μm-thick copper foil and thepreviously surface-treated MCL-E-679 FG were laminated throughGEA-679-FG (trade names; manufactured by Hitachi Chemical Co., Ltd.),which are prepreg, and the resulting laminate was press-formed at 170°C. and 2.45 MPa for 1 hour and subjected to photolithographic treatmentto obtain a sample having a conductor with 1 mm width for peel strengthmeasurement.

Production of Evaluation Sample of Example 2C

A sample was produced in the same manner as the evaluation sample 1C foradhesion strength evaluation, except that in place of the resincomposition A, the resin composition A-2 was applied to the bright face(Rz=0.6 μm) of the un-treated 18 μm-thick copper foil.

Production of Evaluation Sample of Example 3C

A sample was produced in the same manner as the evaluation sample 1C foradhesion strength evaluation, except that in place of the resincomposition A, the resin composition A-3 was applied to the bright face(Rz=0.6 μm) of the un-treated 18 μm-thick copper foil.

Production of Evaluation Sample of Example 4C

A sample was produced in the same manner as the evaluation sample 1C foradhesion strength evaluation, except that in place of the resincomposition A, the resin composition A-4 was applied to the bright face(Rz=0.6 μm) of the un-treated 18 μm-thick copper foil.

Production of Evaluation Sample of Comparative Example 1C

A sample was produced in the same manner as the evaluation sample 1C foradhesion strength evaluation, except that no resin composition A wasapplied.

Measurement of Conductor Peel Strength

The peel strengths of the conductors of the evaluation samples ofExamples 1C to 4C and the comparative Example 1C were measured. Themeasurement method and the conditions were as those of Examples 1B to 5Band Comparative Examples 1B and 2B.

Measurement of Moisture Absorption Heat Resistant Test

The moisture absorption heat resistant test of the evaluation samples ofExamples 1C to 4C and the comparative Example 1C was carried out. Themeasurement method and the conditions were as those of Examples 1B to 5Band Comparative Examples 1B and 2B, and blister occurrence thesubstrates was confirmed. The test of the evaluation samples was carriedout by measuring the peel strength of the samples after 96 hourtreatment.

Measurement of Connection Reliability

The connection reliability of the substrates of Examples 1C to 4C andthe comparative Example 1C was evaluated. The connection reliabilityevaluation method was same as that in Examples 1B to 5B and ComparativeExamples 1B and 2B

Test Results

The test results are shown in Table 10. The substrates and theevaluation samples produced in Examples 1C to 4C were found havingconductor peel strength as high as 0.7 kN/m or higher in all cases; inan initial stage, after treatment at 150° C. for 240 hours, and afterthe moisture absorption heat resistance test. Further, no blisteroccurred after the moisture absorption heat resistance test, showinggood connection reliability.

On the other hand, the substrate and the evaluation sample produced inComparative Example 1C were found having weak conductor peel strengthand causing blister between the inner conductor and the insulating layerafter the moisture absorption heat resistance test. Also, no goodconnection reliability was obtained.

TABLE 10 Conductor Peel Strength (kN/m) Blist After Moisture AfterMoisture Initial After Treatment at Absorption Heat Absorption HeatConnection Stage 150° C. for 240 hours Resistance Test Resistance TestReliability Example 1 1.1 0.9 0.9 None Good Example 2 1.1 0.8 0.8 NoneGood Example 3 1.2 0.8 0.8 None Good Example 4 1 0.7 0.7 None GoodComparative 0.3 0.2 0 Caused Inferior Example 1

According to the embodiments of the invention, without carrying outtreatment of a conductor circuit, an inner conductor circuit treatmentmethod giving good electric properties, suppressing risk of wiringunevenness and defects, and improving good reliability is provided.

It should be understood that the foregoing relates to only preferredembodiments of the invention, and it is intended to cover all changesand modifications of the examples of the invention herein chosen for thepurposes of the disclosure, which do not constitute departures from thespirit and scope of the invention.

1. An inner conductor circuit treatment method involving forming apolyamide imide layer as an adhesion promoting agent on a core substratebearing a conductor circuit, wherein the conductor circuit has ten-pointmean surface roughness (Rz) of 2.0 μm or less, forming an insulatinglayer on the polyamide imide layer, and forming a pattern circuit on theinsulating layer.
 2. The inner conductor circuit treatment methodaccording to claim 1, wherein the thickness of the polyamide imide layeris 0.1 to 5 μm.
 3. The inner conductor circuit treatment methodaccording to claim 1, wherein the polyamide imide layer is formed byimmersing the core substrate bearing the conductor circuit in apolyamide imide solution.
 4. The inner conductor circuit treatmentmethod according to claim 3, wherein after immersion to the polyamideimide solution, the polyamide imide is set in B stage state by dryinguntil the remaining solvent is decreased to 1% or less.
 5. The innerconductor circuit treatment method according to claim 1, wherein theconductor circuit is made of copper and the polyamide imide layer isformed directly on the copper without any practical surface-rougheningtreatment.
 6. The inner conductor circuit treatment method according toclaim 1, wherein the insulating layer contained in the core substratehas ten-point mean surface roughness (Rz) of 2.0 μm or less.
 7. Theinner conductor circuit treatment method according to claim 1, wherein apolyamide imide of the polyamide imide layer includes a saturatedhydrocarbon in a repeating unit.
 8. The inner conductor circuittreatment method according to claim 1, wherein the insulating layercontains at least an epoxy resin.
 9. The inner conductor circuittreatment method according to claim 1, wherein the insulating layer ismade of prepreg.
 10. The inner conductor circuit treatment methodaccording to claim 1, wherein said polyamide imide layer formed has athickness of 0.1 to 10 μm.
 11. The inner conductor circuit treatmentmethod according to claim 7, wherein said polyamide imide layer formedhas a thickness of 0.1 to 5 μm.
 12. The inner conductor circuittreatment method according to claim 1, wherein polyamide imide of thepolyamide imide layer includes an alicyclic hydrocarbon group in arepeating unit.